A method for preparing a long-lasting stable perovskite photovoltaic device

Abstract

The present invention is a method for preparing a long-term stable perovskite photovoltaic device, which utilizes a dynamic optimization packaging strategy of photodeformable molecules for the perovskite interface to achieve long-term passivation of the perovskite film and continuous interception of iodine ion diffusion. The method of the present invention provides a complete set of method steps for preparing a long-term stable photovoltaic device, starting from the selection of perovskite materials and the matching of device structures to the interface engineering optimization strategy. This dynamic passivation and internal packaging method can effectively improve the photostability of the perovskite photovoltaic device. After 1200 hours of full spectrum illumination, the optimized device still maintains 99% of the initial efficiency, and after 450 hours of ultraviolet illumination, the optimized device still maintains 93% of the initial efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic devices, and in particular to a method for preparing a long-lasting and stable perovskite photovoltaic device. Background Art

[0002] The certified efficiency of perovskite solar cells, which have attracted much attention in recent years, has now reached more than 25%, gradually reaching a level comparable to the more mature and commercialized inorganic photovoltaic industry, including silicon cells, thin-film copper indium gallium selenide and cadmium telluride. This means that efficiency is no longer a problem that limits the commercialization of perovskites. Therefore, the current research direction is also more committed to overcoming the device stability problems caused by oxygen, water, light, heat, etc. For photovoltaic devices, light stability is the most unavoidable and need to be faced directly, and it is also difficult to improve through external packaging strategies. On the one hand, light can cause defects, which in turn cause defect-induced photodegradation; on the other hand, light is the main factor causing the migration and diffusion of halogen ions. Due to the limited improvement of stability in this aspect by existing external packaging, more research strategies are also focused on internal packaging methods, such as interface engineering strategies, electrode selection, and 2D / 3D perovskite structures. These strategies have achieved certain results and have extended the life of the device to a certain extent. However, the above strategies are all static and have completed their full effects in the preparation stage. Correspondingly, the degradation of perovskite under light and the attenuation process of the device are dynamic and continue to occur and proceed during operation. This mismatch phenomenon has largely curbed the effectiveness of these strategies, which is out of reach for the adverse factors caused by continuous updates in the later stages. Therefore, there is an urgent need for a dynamic strategy to match the dynamics of defect generation to further improve the stability of the device, so as to prepare long-lasting and stable perovskite photovoltaic devices and provide guidance for subsequent development and research. Summary of the invention

[0003] The purpose of the present invention is to overcome the problems existing in the prior art and provide a method for preparing a long-lasting and stable perovskite photovoltaic device. By introducing photodeformable molecules to realize a dynamic packaging method, sustainable dynamic passivation of photogenerated defects and continuous inhibition and interception of the diffusion of continuously generated iodine ions are achieved, thereby forming a long-lasting and stable perovskite photovoltaic device.

[0004] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0005] A method for preparing a long-lasting stable perovskite photovoltaic device, using a dynamic optimization strategy of photodeformable molecules for the perovskite interface, is used to achieve long-lasting passivation of the perovskite film and continuous interception of iodine ion diffusion, and the specific steps are as follows:

[0006] Step 1) Screening of perovskite materials: Selecting mature, efficient and stable perovskite systems;

[0007] Step 2) Select a high-performance device structure based on step 1): Use the existing mature, efficient and stable perovskite solar cell structure;

[0008] Step 3) Screening of photodeformable molecules: Selecting molecular materials that will change under different lighting conditions. Such materials have different passivation sites before and after deformation to produce different passivation effects.

[0009] Step 4) Dry the cleaned FTO transparent conductive glass substrate, treat it with UV for 25 minutes, and then spin coat SnO 2 The electron transport layer is deposited on the substrate and annealed;

[0010] Step 5) Interface optimization packaging material: Dissolve the photodeformable molecule at 4 mg / mL in isopropyl alcohol IPA / chlorobenzene CB with a volume ratio of 1 / 1 to prepare a photodeformable molecule solution for standby use;

[0011] Step 6) Preparation of perovskite precursor solution: 1139 mg of FAPbI 3 42 mg of MACl was dissolved in a mixed solvent of 800 μL of DMF and 200 μL of DMSO and stirred at 25 °C overnight;

[0012] Step 7) Deposit SnO 2 The substrate is placed in an ozone machine for treatment and then taken out and transferred to a glove box, and the perovskite precursor solution prepared in step 6) is spin-coated on the substrate by spin coating. After spin coating, the substrate is transferred to a heating table for preliminary annealing to obtain a perovskite film;

[0013] Step 8) performing photodeformation-type molecule optimization encapsulation treatment on the prepared perovskite film, spin-coating the photodeformation-type molecule solution prepared in step 5) on the perovskite film substrate, and moving it to a heating table to complete annealing treatment;

[0014] Step 9) processing a hole transport layer Sprio-OMeTAD on the thin film prepared in step 8) by spin coating, and preparing a hole transport layer by spin coating;

[0015] Step 10) Depositing thin film molybdenum trioxide and silver electrode on the hole transport layer prepared in step 9) by thermal evaporation technology.

[0016] Preferably, in step 1), the mature, efficient and stable perovskite system includes MAPbI 3 、((CsFAMA)Pb(I 1-x Br x )3 and FAPbI 3 The reference conditions are the photoelectric performance of photovoltaic devices prepared with the same device structure under AM1.5 conditions, among which FAPbI 3 System is appropriate.

[0017] Preferably, in step 2), the existing mature, efficient and stable perovskite solar cell structure includes an inverted structure ITO or FTO / TiO 2 or SnO 2 / Perovskite layer / Sprio-OMetAD or PTAA / MoO 3 / Ag orAu and ortho-structured ITO or FTO / PEDOT or PTAA / Perovskite / PCBM or P3HT / Ag or Au. The reference conditions are the photoelectric performance of photovoltaic devices prepared with the same main perovskite materials under AM1.5 conditions. Among them, the mature, efficient and stable FTO / SnO 2 / Perovskite / Sprio-OMeTAD / Ag inverted device structure is suitable for preparing stable photovoltaic devices.

[0018] Preferably, the photodeformable molecules in step 3) include molecules with photoisomerization and photo-induced molecular formula transformation, and the reference conditions selected are whether they have different active sites and different passivation effects before and after deformation to meet different passivation requirements, among which photoisomerization type spiropyran molecules are preferred.

[0019] Preferably, the structure and morphological transformation of the selected spiropyran molecules are as shown in Formula 1: ...Formula 1.

[0020] Preferably, in step 4), the spin coating condition is 3000 rpm / 30 s, and the annealing condition is 150° C. / 30 min.

[0021] Preferably, the spin coating condition in step 7) is a one-step method at 5000 rpm / 30 s, and 700 μL of ether is added dropwise as an anti-solvent at 15 s, and the annealing condition is 150° C. / 10 min.

[0022] Preferably, the spin coating condition in step 8) is 4000 rpm / 30 s, and the annealing condition is 100° C. / 5 min.

[0023] Preferably, the spin coating condition in step 9) is 5000 rpm / 40 s.

[0024] Preferably, the thicknesses of the thin film molybdenum trioxide and the silver electrode in step 10) are 10 nm and 100 nm respectively.

[0025] The beneficial effects of the present invention are:

[0026] The method of the present invention achieves sustainable dynamic passivation of photogenerated defects and continuous suppression and interception of the diffusion of continuously generated iodine ions by optimizing the encapsulation of the perovskite surface with photodeformable molecules to achieve the preparation of stable perovskite photovoltaic devices. This novel dynamic encapsulation strategy well matches the dynamics of defect generation and device degradation, effectively improves the photostability of perovskite films and devices, and can still maintain device efficiency well under long-term illumination. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the optimized internal encapsulation treatment of perovskite film surface by spiropyran molecules;

[0028] Figure 2 JV test curves of photovoltaic devices before and after treatment;

[0029] Figure 3 This is the UV-visible absorption spectrum of spiropyran molecules after being irradiated with light in different wavelengths for fifteen minutes;

[0030] Figure 4 Schematic diagram of the mechanism of improving device stability based on the dynamic encapsulation layer formed by spiropyran molecules;

[0031] Figure 5 PCE attenuation curves of photovoltaic devices placed in different environments before and after processing: (a) device efficiency stability when exposed to UV light in an atmospheric environment (humidity is about 30%); (b) device efficiency stability when exposed to full-spectrum light in a nitrogen environment; (c) device efficiency stability when exposed to white LED light in a nitrogen environment; (d) device efficiency stability in a normal atmospheric environment.

[0032] Figure 6 PCE attenuation curve of the photovoltaic device before and after processing under full-spectrum solar illumination environment. DETAILED DESCRIPTION

[0033] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0034] The FTO substrate, formamidine lead iodide (FAPbI 3) and methylammonium chloride (MACl) were purchased from Liaoning Advanced Election Technology Co., Ltd., dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF) and isopropanol (IPA) were purchased from Alfa Aesar Ltd, and spiropyran molecules were purchased from Macklin Ltd. All materials were used as received. Example

[0035] Photovoltaic device structure: FTO / SnO 2 / Perovskite / Spiro-OMeTAD / MoO 3 / Ag structure to prepare photovoltaic devices.

[0036] The preparation method of the solution in this embodiment is as follows:

[0037] Optimized packaging materials: Spiropyran molecules: Dissolve the molecular powder at 4 mg / ml in isopropyl alcohol (IPA) and chlorobenzene (CB) in a volume ratio of 1 / 1.

[0038] Preparation of perovskite solution: FAPbI 3 (1039 mg) and MACl (42 mg) were dissolved in 1 ml of a DMF / DMSO mixed solvent (volume ratio of 4:1) and heated at 25°C with stirring overnight.

[0039] The preparation process of the long-lasting stable perovskite photovoltaic device in this embodiment is as follows:

[0040] (1) The FTO transparent conductive glass substrate was repeatedly ultrasonically cleaned three times with deionized water, acetone, and ethanol, and then baked for 20 minutes to completely remove the solvent and moisture;

[0041] (2) The treated FTO was then treated with UV light and ozone for 25 minutes;

[0042] (3) SnO 2 The electron transport layer was spin-coated on the FTO substrate and 50 μL of SnO was coated statically. 2 Solution, spin coating condition is 3000rpm / 30s, annealing condition is 150℃ / 30min;

[0043] (4) Deposit the SnO 2The substrate was placed in an ozone machine for 30 minutes and then taken out and transferred to a glove box. The perovskite solution was spin-coated on the substrate by spin coating. After spin coating, the substrate was transferred to a heating table for preliminary annealing. The spin coating method was as follows: 50 μL of perovskite solution was statically coated, one-step method 5000 rpm / 30 s, and 700 μL of ether was added as an anti-solvent at 15 s. The annealing condition was 150 °C / 10 min.

[0044] (5) The perovskite film prepared in the previous step was subjected to spiropyran molecule optimization encapsulation treatment. The prepared spiropyran molecule solution was spin-coated on the perovskite film substrate obtained in the previous step, and moved to a heating table for annealing. 80 μL of the surface optimization molecule solution was spin-dropped. The spin coating conditions were 4000 rpm / 30 s, and the annealing conditions were 100 °C / 5 min.

[0045] (6) Processing the hole transport layer Spiro-OMeTAD on the film prepared in the previous step by spin coating, preparing the hole transport layer by spin coating, statically coating 50 μL of Spiro solution, and the spin coating condition is 5000 rpm / 40 s;

[0046] (7) Thin film molybdenum trioxide and silver electrode are deposited on the hole transport layer prepared in the previous step using thermal evaporation technology.

[0047] Comparative Example

[0048] Photovoltaic device structure: FTO / SnO 2 / Perovskite / Spiro-OMeTAD / MoO 3 / Ag structure to prepare photovoltaic devices.

[0049] The preparation method of the solution in this comparative example is as follows:

[0050] Preparation of perovskite solution: FAPbI 3 (1039 mg) and MACl (42 mg) were dissolved in 1 ml of a DMF / DMSO mixed solvent (volume ratio of 4:1) and heated at 25°C with stirring overnight.

[0051] The preparation process of the perovskite photovoltaic device in this comparative example:

[0052] (1) The FTO transparent conductive glass substrate was repeatedly ultrasonically cleaned three times with deionized water, acetone, and ethanol, and then baked for 20 minutes to completely remove the solvent and moisture;

[0053] (2) The treated FTO was then treated with UV light and ozone for 25 minutes;

[0054] (3) SnO 2The electron transport layer was spin-coated on the FTO substrate and 50 μL of SnO was coated statically. 2 Solution, spin coating condition is 3000rpm / 30s, annealing condition is 150℃ / 30min;

[0055] (4) Deposit the SnO 2 The substrate was placed in an ozone machine for 30 minutes and then taken out and transferred to a glove box. The perovskite solution was spin-coated on the substrate by spin coating. After spin coating, the substrate was transferred to a heating table for preliminary annealing. The spin coating method was as follows: 50 μL of perovskite solution was statically coated, one-step method 5000 rpm / 30 s, and 700 μL of ether was added as an anti-solvent at 15 s. The annealing condition was 150 °C / 10 min.

[0056] (5) The hole transport layer Spiro-OMeTAD was processed by spin coating on the film prepared in the previous step. The hole transport layer was prepared by spin coating, and 50 μL of Spiro solution was statically coated. The spin coating condition was 5000 rpm / 40 s.

[0057] (6) Thin film molybdenum trioxide and silver electrode are deposited on the hole transport layer prepared in the previous step using thermal evaporation technology.

[0058] In summary, the schematic diagram of the optimized internal encapsulation treatment of the perovskite film surface by spiropyran molecules can be found in Figure 1 ,exist Figure 1 It can be seen that the spiropyran molecular layer can serve as an inner encapsulation layer triggered by ultraviolet light.

[0059] exist Figure 2 It can be seen that under AM1.5G illumination, the maximum efficiency of the perovskite photovoltaic device before and after treatment reached 21.96% and 23.23% respectively, and the initial performance of the device was improved to a certain extent after optimization.

[0060] exist Figure 3 It can be seen that spiropyran molecules exist in the form of stable SP under normal visible light irradiation, and partially transform into the metastable MC form after 15 minutes of ultraviolet irradiation. Since sunlight contains both ultraviolet and visible light bands, spiropyran molecules will exist in two forms at the same time under full-spectrum sunlight. For the SP form, it has very few sites that can interact with defects, which allows SP to exist as a combat readiness force when no more photogenerated defects are generated during device operation. For the MC form, it has more sites that can interact with defects, which means that when new defects are generated, it can passivate the newly generated defects in time, thus satisfying the characteristics of dynamic passivation.

[0061] exist Figure 4It can be seen that before the perovskite layer is optimized, when ultraviolet light is present, there will be defects such as vacancy defects or freely diffusing iodine ions in the perovskite. After the introduction of spiropyran molecules, ultraviolet light will promote the photoisomerization of spiropyran molecules from SP form to MC form, thereby effectively passivating the generated photogenerated defects and preventing the diffusion of iodine ions.

[0062] exist Figure 5 As can be seen in the figure, the treated device still maintains 93% of its initial efficiency after about 450 hours of UV irradiation. Figure 5 and Figure 6 As shown in the figure, after about 1200 hours of full-spectrum sunlight illumination, the initial efficiency is still maintained at 99%, after about 500 hours of continuous LED light illumination, the efficiency remains basically stable, and after about 1500 hours of normal exposure to the atmosphere, the efficiency is still maintained at 95%. After comprehensive testing, it was found that the treated device showed significantly improved stability.

[0063] 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 a long-lasting stable perovskite photovoltaic device, characterized in that: The dynamic optimization strategy of photodeformation molecules for the perovskite interface is used to achieve long-term passivation of the perovskite film and continuous interception of iodine ion diffusion. The specific steps are as follows: Step 1) Screening perovskite materials: Select mature, efficient and stable perovskite systems, including MAPbI3, ((CsFAMA)Pb(I1-xBrx)3 and FAPbI3. The reference conditions are the photoelectric performance of photovoltaic devices prepared with the same device structure under AM1.5 conditions; Step 2) Select a high-performance device structure based on step 1): Use the existing mature, efficient and stable perovskite solar cell structure. The existing mature, efficient and stable perovskite solar cell structure includes an inverted structure ITO or FTO / TiO2 or SnO2 / Perovskite layer / Sprio-OMetAD or PTAA / MoO3 / Ag or Au and an upright structure ITO or FTO / PEDOT or PTAA / Perovskite / PCBM or P3HT / Ag or Au. The reference conditions are the photoelectric performance of photovoltaic devices prepared with the same main perovskite material under AM1.5 conditions; Step 3) Screening of photodeformable molecules: Selecting molecular materials that will change under different lighting conditions. Such materials have different passivation sites before and after deformation to produce different passivation effects. Step 4) drying the cleaned FTO transparent conductive glass substrate, treating it with UV for 25 minutes, depositing a SnO2 electron transport layer on the substrate by spin coating, and performing annealing; Step 5) Interface optimization packaging material: Dissolve the photodeformable molecule at 4 mg / mL in isopropyl alcohol IPA / chlorobenzene CB with a volume ratio of 1 / 1 to prepare a photodeformable molecule solution for standby use; Step 6) Prepare the perovskite precursor solution: dissolve 1139 mg of FAPbI3 and 42 mg of MACl in a mixed solvent of 800 μL of DMF and 200 μL of DMSO and stir at 25 °C overnight; Step 7) Place the SnO2-deposited substrate in an ozone machine for treatment and then take it out and transfer it to a glove box. Spin the perovskite precursor solution prepared in step 6) on the substrate by spin coating. After spin coating, transfer the substrate to a heating table for preliminary annealing to obtain a perovskite film. Perform spiropyran molecule optimization encapsulation treatment on the perovskite film prepared in the previous step, spin coat the prepared spiropyran molecule solution on the perovskite film substrate obtained in the previous step, and move it to a heating table to complete annealing. Step 8) performing spiropyran molecule optimization encapsulation treatment on the prepared perovskite film, spin-coating the photodeformation molecule solution prepared in step 5) on the perovskite film substrate, and moving it to a heating table to complete annealing treatment; Step 9) processing a hole transport layer Sprio-OMeTAD on the thin film prepared in step 8) by spin coating, and preparing a hole transport layer by spin coating; Step 10) Depositing thin film molybdenum trioxide and silver electrode on the hole transport layer prepared in step 9) by thermal evaporation technology.

2. The method for preparing a long-lasting stable perovskite photovoltaic device according to claim 1, characterized in that: In the step 1), the mature, efficient and stable perovskite system uses the FAPbI3 system.

3. The method for preparing a long-lasting stable perovskite photovoltaic device according to claim 1, characterized in that: In the step 2), a mature, efficient and stable FTO / SnO2 / Perovskite / Sprio-OMeTAD / Ag inverted device structure is selected to prepare a stable photovoltaic device.

4. The method for preparing a long-lasting stable perovskite photovoltaic device according to claim 1, characterized in that: The photodeformable molecules in step 3) are photoisomerizable spiropyran molecules.

5. The method for preparing a long-lasting stable perovskite photovoltaic device according to claim 4, characterized in that: The structure and morphological transformation of the selected spiropyran molecules are shown in Formula 1: ...Formula 1.

6. The method for preparing a long-lasting stable perovskite photovoltaic device according to claim 1, characterized in that: In the step 4), the spin coating condition is 3000 rpm / 30 s, and the annealing condition is 150° C. / 30 min.

7. The method for preparing a long-lasting stable perovskite photovoltaic device according to claim 1, characterized in that: The spin coating condition in step 7) is a one-step method of 5000 rpm / 30 s, and 700 μL of ether is added dropwise as an anti-solvent after 15 s, and the annealing condition is 150° C. / 10 min.

8. The method for preparing a long-lasting stable perovskite photovoltaic device according to claim 1, characterized in that: The spin coating condition in step 8) is 4000 rpm / 30 s, and the annealing condition is 100° C. / 5 min.

9. The method for preparing a long-lasting stable perovskite photovoltaic device according to claim 1, characterized in that: The spin coating condition in step 9) is 5000 rpm / 40 s.

10. The method for preparing a long-lasting stable perovskite photovoltaic device according to claim 1, characterized in that: The thicknesses of the thin film molybdenum trioxide and the silver electrode in step 10) are 10 nm and 100 nm respectively.

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