Synthesis method of perovskite precursor solution of formamidinium ionic liquid, battery device and solar cell

Abstract

Embodiments of the present invention disclose a synthesis method, a battery device and a solar cell of a formamidinium-based ionic liquid perovskite precursor solution, including: adding organic sodium salt and formamidinium hydrochloride into ethanol respectively, stirring and dissolving to obtain a formamidinium hydrochloride solution and a sodium alkylate solution; dropping the formamidinium hydrochloride solution into the sodium alkylate solution drop by drop, stirring the mixed solution at 25-60 °C, and reacting for 24-36 h; filtering the reacted mixed solution, taking the filtrate, and rotary evaporating the obtained primary filtrate to remove the ethanol solvent, and shaking and washing with an organic solvent for 25-35 min; performing secondary filtration on the washed solution, taking the filtrate, and rotary evaporating the obtained secondary filtrate to remove the organic solvent to obtain an organic acid formamidinium ionic liquid; dissolving lead iodide and formamidinium hydroiodide in the organic acid formamidinium ionic liquid, and reacting at 40-80 °C for at least 5 h to obtain a formamidinium-based ionic liquid perovskite precursor solution. This method solves the problem of poor phase stability of FAPbI3 perovskite in a humid environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic materials, and particularly relates to a synthesis method of a formamidinium ionic liquid-based perovskite precursor solution, a battery device, and a solar cell. Background Art

[0002] Ionic liquids are salts composed of cations and anions and are liquid at room temperature. They have stable properties, weak volatility, and strong solubility in certain inorganic metal halides. At the same time, ionic liquids also have excellent designability and can meet various requirements through the design of cations and anions.

[0003] At present, organic-inorganic hybrid perovskites, as a direct-bandgap semiconductor with ionic characteristics, have received extensive research attention due to their excellent optoelectronic properties and solution-processability. With the continuous optimization of perovskites and related materials, the power conversion efficiency of perovskite solar cells has been rapidly improved, and the current world-certified efficiency has reached 25.8%, which can already be comparable to silicon-based perovskite solar cells.

[0004] The biggest advantage of perovskite solar cells is their solution-processability. The choice of solvent is restricted by lead halide salts, which are slightly or completely insoluble in most solvents in large-scale deposition techniques. In addition, during the preparation of perovskite solar cells, the solvent is crucial for controlling the crystallization and crystal growth of perovskites. However, currently, high-boiling-point, polar, and aprotic solvents such as DMF, DMSO, and GBL are still used in solution techniques to prepare high-efficiency perovskite solar cells. Most of these solvents are highly toxic and require strict management during storage, which is very likely to cause safety accidents. In addition, most current high-efficiency perovskite solar cells use an antisolvent technique, and the antisolvents are some highly toxic and volatile organic solvents such as chlorobenzene, ether, and toluene. Most importantly, the antisolvent technique is very difficult to control during the preparation of perovskite thin films, and the controllable time window is very narrow. Therefore, the repeatability of preparing high-quality perovskite thin films by the antisolvent technique is very poor, especially between different research groups and even between different people in the same research group. Since the antisolvent induces crystallization by volatilization during the preparation process, the preparation environment and atmosphere are also crucial. Therefore, the solvent treatment problem and the toxicology problem pose great challenges to the commercial development of perovskite solar cells.

[0005] Recently, ionic liquids have shown great advantages as solvents in perovskite solar cells, such as ionic liquids with methylamine as the cation, such as methylammonium formate (MAFa), methylammonium acetate (MAAc), and methylammonium propionate (MAPa). However, methylamine-based ionic liquids will affect the crystal composition and structure during the preparation of non-methylamine perovskite solar cells. Especially in the preparation of FAPbI3 perovskite with easy phase change, it will cause a blue shift of the band gap and affect the performance. Summary of the Invention

[0006] An embodiment of the present invention provides a method for synthesizing a perovskite precursor solution of formamidinium ionic liquid, including:

[0007] Adding sodium organic salt and formamidinium hydrochloride into ethanol respectively, stirring and dissolving to obtain a formamidinium hydrochloride solution and a sodium alkylate solution;

[0008] Dropwise adding the formamidinium hydrochloride solution into the sodium alkylate solution, stirring the mixture at 25 - 60 °C for 24 - 36 h;

[0009] Filtering the reacted mixture, taking the filtrate, and rotary evaporating the obtained primary filtrate to remove the ethanol solvent, and shaking and washing with an organic solvent for 25 - 35 min;

[0010] Performing secondary filtration on the washed solution, taking the filtrate, and rotary evaporating the obtained secondary filtrate to remove the organic solvent to obtain an organic acid formamidinium ionic liquid;

[0011] Dissolving lead iodide and formamidinium hydroiodide in the organic acid formamidinium ionic liquid, and reacting at 40 - 80 °C for at least 5 h to obtain a perovskite precursor solution of formamidinium ionic liquid.

[0012] Specifically, the molar ratio of the sodium organic salt to the formamidinium hydrochloride is 1:1.5 - 2.5.

[0013] Furthermore, it further includes:

[0014] Adding the obtained organic acid formamidinium ionic liquid into ethanol for dissolution, and removing ethanol by rotary evaporation, repeating multiple times to obtain a pure alkyl acid formamidinium ionic liquid.

[0015] Preferably, it further includes:

[0016] The molar ratio of the mixture of the sodium organic salt and the formamidinium hydrochloride to ethanol is 1:5 - 8.

[0017] Specifically, the sodium organic salt is at least one of sodium alkylate, sodium propionate, or sodium butyrate.

[0018] An embodiment of the present invention also provides a method for preparing a perovskite battery device, including:

[0019] Clean the conductive glass substrate, spin-coat the electron transport material on the conductive glass substrate, and spin-coat the perovskite precursor solution of the formamidinium ionic liquid prepared by the above synthesis method on the electron transport layer of the conductive glass substrate, and anneal to form a formamidinium perovskite thin film;

[0020] Spin-coat the hole transport layer material on the formamidinium perovskite thin film to obtain a hole transport layer, and evaporate a modification layer and a metal electrode on the hole transport layer.

[0021] Specifically, the preparation of the electron transport layer further includes:

[0022] Mix SnO2 and deionized water in a mass ratio of 1:3 - 7 to obtain the SnO2 solution of the electron transport layer material;

[0023] Use a spin coater to spin-coat the SnO2 solution on the conductive substrate at 3500 - 4500 r / min for 20 - 40 s to form a film, and anneal at 120 - 180 °C for at least 30 min;

[0024] Perform ultraviolet ozone treatment on the conductive substrate spin-coated with the electron transport layer after annealing for at least 10 min.

[0025] Specifically, the preparation of the hole transport layer further includes:

[0026] Dissolve Spiro-OMeTAD in chlorobenzene, stir, and add a lithium bis(trifluoromethanesulfonyl)imide acetonitrile solution and 4-tert-butylpyridine to form a hole transport layer material;

[0027] Under the condition of 3500 - 4500 r / min, spin-coat the hole transport layer material on the surface of the AgBiS2 active layer for 20 - 40 s to form a film, and oxidize in air for at least 24 h.

[0028] Specifically, the modification layer is MoO3, with a thickness of 3 - 7 nm, and the metal electrode is Au or Ag, with a thickness of 80 - 120 nm.

[0029] An embodiment of the present invention also provides a solar cell, including the perovskite battery device as described above.

[0030] The synthesis method of the perovskite precursor solution of the formamidinium ionic liquid provided by the embodiment of the present invention is applied to the preparation of the FAPbI3 perovskite thin film. It can be completed in air, and can realize the one-step preparation of the pure-component FAPbI3 perovskite thin film in air, solving the problem of poor phase stability of FAPbI3 perovskite in a humid environment. The FAPbI3 perovskite thin film prepared by this method has uniform crystallinity, is dense and has stable components. The preparation process has low cost, simple operation, low-temperature operation, and is easy to scale up, which is of great significance for the future large-scale production of high-efficiency perovskite solar cells. Brief Description of the Drawings

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those skilled in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0032] Figure 1 is a physical diagram of the alkyl acid formamidine ionic liquid provided by the embodiment of the present invention;

[0033] Figure 2 is the chemical reaction equation provided by the embodiment of the present invention;

[0034] Figure 3 is the structural diagram of the perovskite device provided by the embodiment of the present invention;

[0035] Figure 4 is the XRD pattern of the perovskite thin film provided by the embodiment of the present invention;

[0036] Figure 5 is the J-V curve diagram of the perovskite device in Example 1 provided by the embodiment of the present invention;

[0037] Figure 6 is the J-V curve diagram of the perovskite device in Example 2 provided by the embodiment of the present invention. Detailed Embodiments

[0038] To enable those skilled in the art to better understand the solution of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention.

[0039] Example 1

[0040] 1. Sodium propionate and formamidine hydrochloride are respectively added to a single-necked flask containing ethanol, and stirred at room temperature for 24 h until completely dissolved. The completely dissolved formamidine hydrochloride is added dropwise to the single-necked flask containing sodium propionate, and the mixed solution in the single-necked flask is magnetically stirred under the condition of 25-60 °C. After stirring for 24-36 h, the reaction is stopped.

[0041] 2. The reaction solution obtained in step 1 is filtered once, and the ethanol solvent in the first-stage filtrate after filtration is removed by rotary evaporation. Then, it is washed with acetone or benzene for 20-35 min, and the washed solution is filtered a second time to remove the excess solid. After that, the second-stage filtrate after filtration is rotary evaporated to remove the acetone or benzene solvent to obtain the required propionic acid formamidine ionic liquid, as Figure 1 shown.

[0042] 3. Weigh 291.33 mg of lead iodide and 108.67 mg of formamidinium hydroiodide, dissolve the two in 1 ml of formamidinium ionic liquid solvent of propionic acid, with a molar ratio of 1:1, a concentration of 300 - 600 mg / ml, and react the prepared precursor solution at 60 °C for 5 h, as Figure 2 shown in the reaction formula.

[0043] 4. Clean the ITO conductive glass in the following order: ethanol with cleaning agent, ultrapure water with cleaning agent, ultrapure water, acetone, and ethanol, each with ultrasonic treatment for 10 min, dry with nitrogen to obtain a clean conductive glass substrate, and perform ultraviolet ozone treatment for 15 minutes.

[0044] 5. Dilute 1 ml of SnO2 with ultrapure water to 2.67 wt%. Take 45 μL of the diluted SnO2 and drop it onto the ITO substrate, and use a spin coater to form a film at a rotation speed of 3000 r / min for 30 seconds. Anneal the ITO coated with SnO2 at 150 °C for 30 min. Place the annealed ITO conductive substrate coated with the electron transport layer on a hot spin coater and preheat for 5 min.

[0045] 6. Take 80 μL of the perovskite precursor solution after the reaction in step 3 and drop it onto the preheated ITO substrate, spin coat to form a film, and then anneal to form a perovskite film. The rotation speed for spin coating the perovskite precursor solution is 4000 r / min for 30 seconds, and anneal at 150 °C for 30 min in dry air.

[0046] 7. Weigh 73.2 mg of Spiro - MeOTAD, dissolve it in 1 ml of chlorobenzene solvent, stir and dissolve for 1 hour, then add 17.6 μL of lithium bis(trifluoromethanesulfonyl)imide dissolved in acetonitrile, with a concentration of 520 mg / ml, stir and dissolve for 1 hour, and finally add 28.8 μL of 4 - tert - butylpyridine and stir and dissolve for 1 hour to obtain the hole transport layer material, and spin coat it on the perovskite film. The rotation speed for spin coating Spiro - MeOTAD is 3000 r / min for 30 seconds to form the hole transport layer, and oxidize in air for 24 h.

[0047] 8. Using vacuum evaporation technology, evaporate 5 nm of MoO3 on the hole transport layer, and then evaporate 100 nm of metal electrode Ag to obtain a perovskite solar cell device, as Figure 3 shown in the structural diagram. As Figure 4 shown, a strong black - phase FAPbI3 perovskite can be obtained at 13.9°. As Figure 5 and Figure 6 shown, under standard test conditions (AM1.5G illumination), the energy conversion efficiency of the battery device prepared in this example is 16.5%, the open - circuit voltage is 0.976 V, and the short - circuit current is 26.17 mA / cm2 , the fill factor is 64.66%.

[0048] Example 2

[0049] 1. Add sodium butyrate and formamidine hydrochloride into a single-necked flask filled with ethanol respectively, and stir for 24 h at room temperature until completely dissolved; gradually add the completely dissolved formamidine hydrochloride dropwise into the single-necked flask containing sodium butyrate, and magnetically stir the mixed solution in the single-necked flask at 25 - 60 °C for 24 - 36 h, then stop the reaction.

[0050] 2. Filter the obtained reaction solution once, and rotary evaporate the ethanol solvent from the first-stage filtrate after filtration. Then, wash it with acetone or benzene by shaking for 20 - 35 min, filter the washed solution a second time to remove the excess solid, and rotary evaporate the acetone or benzene solvent from the second-stage filtrate after filtration to obtain the desired formamidinium butyrate ionic liquid.

[0051] 3. Weigh 291.33 mg of lead iodide and 108.67 mg of formamidinium hydroiodide, dissolve the two in 1 ml of formamidinium butyrate ionic liquid solvent, and react at 40 °C for 6 h.

[0052] 4. Clean the ITO conductive glass in the following order: ultrasonic in ethanol with cleaning agent, ultrapure water with cleaning agent, ultrapure water, acetone, and ethanol for 15 min each, dry it with nitrogen, and then perform ultraviolet ozone treatment for 20 minutes after obtaining a clean conductive glass substrate.

[0053] 5. Dilute 1 ml of SnO2 with ultrapure water to 2.67 wt%. Take 45 μL of the diluted SnO2 and drop it onto the ITO substrate, and spin-coat it into a film at a rotation speed of 3000 r / min for 30 s. Anneal the ITO coated with SnO2 at 150 °C for 30 min. Place the annealed ITO conductive substrate coated with the electron transport layer on a hot spin coater and preheat it for 5 min.

[0054] 6. Take 80 μL of the reacted perovskite precursor solution and drop it onto the preheated ITO substrate, spin-coat it into a film, and then anneal it to form a perovskite film. The rotation speed for spin-coating the perovskite precursor solution is 4000 r / min for 30 s, and anneal it at 150 °C for 30 min in dry air.

[0055] 7. Weigh 73.2 mg of Spiro-MeOTAD, completely dissolve it in 1 ml of chlorobenzene solvent, stir for 1 hour, then add 17.6 μL of lithium bis(trifluoromethanesulfonyl)imide dissolved in acetonitrile, with a concentration of 520 mg / ml, stir for 1 hour, and finally add 28.8 μL of 4-tert-butylpyridine and stir for 1 hour. Spin-coat the obtained hole transport material onto the perovskite film. The spin-coating of Spiro-MeOTAD is carried out at 3000 r / min for 30 seconds to form a hole transport layer, and it is oxidized in air for 24 h.

[0056] 8. Using the vacuum evaporation technique, evaporate 5 nm of MoO3 on the hole transport layer, and then evaporate 100 nm of the metal electrode Au to obtain a perovskite solar cell device. Under standard test conditions (AM1.5G illumination), the energy conversion efficiency of the battery device prepared in this example is 15.47%, the open-circuit voltage is 0.958 V, and the short-circuit current is 25.98 mA / cm 2 , and the fill factor is 62.20%.

[0057] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

[0058] The above are only some implementation manners of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as within the protection scope of the present invention.

Claims

1. A synthesis method of a perovskite precursor solution of formamidinium ionic liquid, characterized in that, Comprising: Sodium alkylate and formamidine hydrochloride are respectively added to ethanol and stirred to dissolve, obtaining a formamidine hydrochloride solution and a sodium alkylate solution; The formamidine hydrochloride solution is added dropwise to the sodium alkylate solution, and the mixture is stirred under the condition of 25 - 60 °C for 24 - 36 h; The reacted mixture is filtered, the filtrate is taken, and the obtained primary filtrate is rotary evaporated to remove the ethanol solvent, and washed with an organic solvent by shaking for 25 - 35 min; The washed solution is filtered for the second time, the filtrate is taken, and the obtained secondary filtrate is rotary evaporated to remove the organic solvent, obtaining an alkyl formamidine ionic liquid; Lead iodide and formamidine hydroiodide are dissolved in the alkyl formamidine ionic liquid, and reacted at 40 - 80 °C for at least 5 h to obtain a perovskite precursor solution of formamidinium ionic liquid.

2. The synthesis method according to claim 1, characterized in that, The molar ratio of sodium alkylate to formamidine hydrochloride is 1:1.5 - 2.

5.

3. The synthesis method according to claim 1, characterized in that, Also comprising: The obtained alkyl formamidine ionic liquid is added to ethanol for dissolution, and ethanol is removed by rotary evaporation, and this is repeated multiple times to obtain a pure alkyl formamidine ionic liquid.

4. The synthesis method according to claim 1, wherein, Also comprising: The molar ratio of the mixture of sodium alkylate and formamidine hydrochloride to ethanol is 1:5 - 8.

5. The synthesis method according to claim 1, wherein The sodium alkylate is at least one of sodium propionate or sodium butyrate.

6. A preparation method of a perovskite battery device, characterized in that Comprising: Clean the conductive glass substrate, spin - coat the electron - transporting material on the conductive glass substrate, and spin - coat the perovskite precursor solution of formamidinium ionic liquid prepared by the synthesis method according to any one of claims 1 to 5 on the electron - transporting layer of the conductive glass substrate, and anneal to form a formamidinium perovskite thin film; Spin - coat a hole - transporting layer material on the formamidinium perovskite thin film to obtain a hole - transporting layer, and evaporate a modification layer and a metal electrode on the hole - transporting layer.

7. The preparation method according to claim 6, characterized in that, Also comprising: Mix SnO2 and deionized water according to a mass ratio of 1:3 - 7 to obtain an SnO2 solution as the electron - transporting layer material; Use a spin - coater to spin - coat the SnO2 solution on the conductive substrate at 3500 - 4500 r / min for 20 - 40 s to form a film, and anneal at 120 - 180 °C for at least 30 min; Perform ultraviolet ozone treatment on the conductive substrate with the spin - coated electron - transporting layer after annealing for at least 10 min.

8. The preparation method according to claim 6, characterized in that, Also comprising: Dissolve Spiro - OMeTAD in chlorobenzene, stir, and add a lithium bis(trifluoromethanesulfonyl)imide acetonitrile solution and 4 - tert - butylpyridine to form a hole - transporting layer material; Under the condition of 3500 - 4500 r / min, spin - coat the hole - transporting layer material on the surface of the AgBiS2 active layer for 20 - 40 s to form a film, and oxidize in air for at least 24 h.

9. The preparation method according to claim 6, characterized in that, The modification layer is MoO3 with a thickness of 3 - 7 nm, and the metal electrode is Au or Ag with a thickness of 80 - 120 nm.

10. A solar cell, comprising the perovskite battery device according to any one of claims 6 to 9.

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