A method and application of preparing formamidite-based FAPbI3 perovskite solar cells by a one-step method at low temperature in air

Abstract

The present invention relates to a method and application for preparing a formamidite-based FAPbI3 perovskite solar cell at low temperature in air, and belongs to the field of optoelectronic materials and devices. The invention dissolves lead iodide and iodoformamidite in a proton-type ionic liquid solution at a stoichiometric ratio of 1:1 to prepare a perovskite precursor solution, which is stirred and reacted at a high temperature of 90°C for 36 hours. The precursor solution is spin-coated on an ITO or FTO conductive substrate that already has a hole transport layer or an electron transport layer in air by a one-step heating spin coating technique, and the transformation of the black phase perovskite can be achieved at room temperature. Then, the electron transport layer or the hole transport layer is spin-coated on the film, and the modification layer and the metal Ag electrode are evaporated by vacuum evaporation technology.

Description

Technical Field

[0001] The present invention relates to a method for preparing formamidino FAPbI in a low temperature one-step process in air based on proton type ionic liquid as solvent. 3 Methods and applications of perovskite solar cells, especially a method for making formamidite-based FAPbI 3 The invention relates to a new method for preparing perovskite solar cells at low temperature in air, belonging to the field of optoelectronic materials and technology. Background Art

[0002] Organic-inorganic hybrid perovskite, as a direct bandgap semiconductor with ionic properties, has received extensive research attention due to its excellent photoelectric properties and solution preparation. With the continuous optimization of perovskite and its related materials, the photoelectric conversion efficiency of perovskite cells has been rapidly improved. The current world certified efficiency has reached 25.5%, which is comparable to silicon-based perovskite solar cells.

[0003] The high perovskite efficiency is mainly due to the guanidine-based perovskite, which has a wide absorption wavelength and excellent thermal stability, and has therefore attracted widespread attention in the field of perovskite solar cell research. However, this type of material is easily converted from the α phase with excellent photoelectric performance to the δ phase with extremely poor photoelectric performance, especially under high humidity conditions, and the service life of the prepared devices is often very short. In addition, the guanidine-based perovskite needs to be realized at high temperatures (above 160°C), which seriously hinders the further development of perovskite solar cells. Therefore, it is of great significance to develop a method for preparing phase-stable guanidine-based perovskites at low temperatures. Summary of the invention

[0004] The technical problem solved by the present invention is to 3 Perovskite has poor phase stability in a humid environment, requires an annealing temperature of more than 150°C in conventional methods, and requires the addition of additional additives. A method and application of preparing formamidite-based FAPbI3 perovskite solar cells in a low-temperature one-step process in air is proposed.

[0005] In order to solve the above technical problems, the technical solution proposed in the present invention is: a method for preparing a formamidite-based FAPbI3 perovskite solar cell in a low-temperature one-step process in air, comprising the following steps:

[0006] (1) dissolving lead iodide and iodoformamidine in a proton-type ionic liquid methylamine acetate solution at a molar ratio of 1:1 to prepare a perovskite precursor solution;

[0007] (2) The precursor solution was stirred and reacted at a high temperature of 90°C for 36 hours to achieve ion recombination and construct a pre-perovskite structure;

[0008] (3) Spin coating a hole or electron transport material onto an ITO or FTO conductive substrate;

[0009] (4) Spin coating the prepared perovskite precursor solution on an ITO or FTO conductive substrate with a hole transport layer or an electron transport layer, and annealing at 40° C.-120° C. for 5 min to obtain a dense and uniform active layer;

[0010] (5) spin coating an electron or hole transport layer on the perovskite layer;

[0011] (6) Vacuum evaporating a modification layer and a metal electrode on the electron or hole transport layer.

[0012] Preferably, the concentration of the perovskite precursor solution in step (1) is 200-600 mg / ml.

[0013] Preferably, the hole transport layer spin-coated on the transparent conductive ITO glass in step (3) is PEDOT:PSS, PTAA or NiOx; the electron transport layer is CPTA, SnO 2 or TiO 2 .

[0014] Preferably, the electron transport layer spin-coated on the perovskite layer is PCBM, and the hole transport layer is Spiro-MeOTAD; the specific steps are as follows:

[0015] (1) Dissolve PCBM in chlorobenzene at a concentration of 18 mg / ml;

[0016] (2) 72.6 mg / ml Spiro-MeOTAD was dissolved in chlorobenzene, stirred for one hour, and then 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide dissolved in acetonitrile was added to a concentration of 520 mg / ml, and finally 29 μL of 4-tert-butylpyridine was added;

[0017] Preferably, the modification layers are LiF, MoO 3 , the metal electrode is Au, Ag or Al. The specific steps are as follows:

[0018] (4) LiF was evaporated on the electron transport layer of the reverse structure with a thickness of 2 nm;

[0019] (5)MoO 3 Evaporated on the hole transport layer in the upright structure with a thickness of 5 nm;

[0020] (6) The thickness of the metal electrode is 100 nm;

[0021] In order to solve the above technical problems, another technical solution proposed by the present invention is: any of the proton-type ionic liquids is used as a solvent to prepare the formamidine FAPbI at low temperature in air. 3New method for preparing perovskite solar cells.

[0022] In order to solve the above technical problems, another technical solution proposed by the present invention is: the proton-type ionic liquid is used as a solvent to prepare the formamidine FAPbI at low temperature in air. 3 New approaches to perovskite solar cells for applications in optoelectronics.

[0023] The perovskite solar cells described are of two structures: reverse and upright planar heterojunction perovskite solar cells.

[0024] Beneficial effects of the present invention:

[0025] (1) The ionic liquid solvent was used to prepare the guanidine-based FAPbI by regulating the ion recombination of the precursor solution. 3 Perovskite, compared with the traditional DMF solvent, the present invention greatly reduces the 3 The temperature of the perovskite phase transition;

[0026] (2) Ionic liquids have anion-cation hybrid structures, and the reaction conditions can be controlled to control the interaction between anions and PbI 2 The interaction of PbI 2 The structure changes from edge-sharing to corner-sharing structure, which is the closest to the perovskite structure, so the transition to the perovskite phase can be achieved quickly.

[0027] (3) The entire perovskite film is prepared in air, solving the problem of FAPbI 3 The problem of poor phase stability of perovskite in humid environment.

[0028] (4) Prepared FAPbI with uniform crystallinity, density and stability 3 Perovskite.

[0029] (5) The film can be prepared by a simple one-step spin coating method. The entire preparation process is low-cost, simple to operate, and requires low-temperature operation.

[0030] (6) Applicable to forward and reverse device structures.

[0031] (7) The ionic liquid solvent ion recombination method not only prepared stable FAPbI in air 3 Perovskite and the prepared perovskite devices have high conversion efficiency. This method is helpful for the preparation of large-area and flexible devices of perovskite solar cells.

[0032] (8) Compared with conventional methods, the present invention does not require any auxiliary solvent to assist crystallization, can achieve one-step preparation, and does not require the addition of additional additives.

[0033] (9) Phase transition can be achieved at room temperature, without the need for annealing temperatures above 150°C as in conventional methods. Figure 1 shown.

[0034] (10) Figure 2 It shows that as the reaction time of the precursor solution increases, the black phase of FAPbI 3 Perovskite appears, and when the reaction time increases to more than 20 h, the solution can directly realize FAPbI 3 Perovskite transformation. Currently, there is no research that can control the reaction of the precursor solution to control FAPbI 3 Phase transitions of perovskites.

[0035] (11) Figure 3 It is shown that as the reaction time of the precursor solution increases, the film gradually changes from transparent color to black perovskite. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below in conjunction with the accompanying drawings.

[0037] Figure 1 It is the X-ray diffraction diagram of the present invention at different annealing temperatures.

[0038] Figure 2 It is an X-ray diffraction diagram of the effect of the precursor solution of the present invention on the film as the reaction time increases.

[0039] Figure 3 This is a graph showing the effect of the precursor solution of the present invention on the film as the reaction time increases;

[0040] Figure 4 It is the X-ray diffraction pattern of the present invention.

[0041] Figure 5 It is a preparation process flow chart of the present invention.

[0042] Figure 6 It is a schematic diagram of the structure of a solar cell device according to Example 1 of the present invention.

[0043] Figure 7 It is a JV curve diagram of energy conversion efficiency of the upright structure solar cell of the present invention.

[0044] Figure 8 It is a schematic diagram of the structure of a solar cell device according to Example 2 of the present invention.

[0045] Fig. 9 It is a JV curve diagram of the energy conversion efficiency of the inverted structure solar cell of the present invention. DETAILED DESCRIPTION

[0046] Example 1

[0047] This example is a method for preparing formamidino FAPbI using the ionic liquid methylamine acetate (MAAc) of the present invention as a solvent in air at low temperature. 3 A planar heterojunction perovskite solar cell is placed upright to facilitate a full understanding of the present invention. The main steps include:

[0048] Step 1) Weigh 281.6 mg of lead iodide and 81.5 mg of iodoformamidine, and dissolve them in 1 ml of MAAc solvent.

[0049] Step 2) The precursor solution prepared in step 1) is reacted at 90° C. for 36 hours, with precise control of temperature and time.

[0050] Step 3) Clean the ITO conductive glass by adding ethanol, ultrapure water, cleaning agent, ultrapure water, acetone, and ethanol in the order of 10 minutes each, and blow dry with nitrogen to obtain a clean conductive glass substrate.

[0051] Step 4) The ITO substrate cleaned in step 2) is treated with ultraviolet ozone for 15 minutes.

[0052] Step 5) Take SnO 2 1 ml was diluted with ultrapure water to 2.67 wt%.

[0053] Step 6) Take the diluted SnO 2 45 μL was dropped onto the ITO substrate treated in step 4) and a film was formed by spin coating at a speed of 3000 rpm for 30 seconds. 2 The ITO was annealed at 150°C for 30 min.

[0054] Step 7) placing the ITO conductive substrate with the electron transport layer spun on it after annealing in step 6) on a hot spin coater and preheating for 5 minutes.

[0055] Step 8) Take 80 μL of the perovskite precursor solution after the reaction in step 2) and drop it onto the preheated ITO substrate in step 7), spin-coat it into a film, and then anneal it to form a perovskite film. The spin-coating speed of the perovskite precursor solution is 4000 revolutions per minute for 20 seconds, and anneal it in air at 100° C. for 5 minutes.

[0056] Step 9) Weigh 73.2 mg of Spiro-MeOTAD and completely dissolve it in 1 ml of chlorobenzene solvent, stirring and dissolving for 1 hour, then add 17.6 μL of lithium bis(trifluoromethanesulfonamide) dissolved in acetonitrile at a concentration of 520 mg / ml and stirring and dissolving for 1 hour, finally add 28.8 μL of 4-tert-butylpyridine and stirring and dissolving for 1 hour.

[0057] Step 10) Spin-coat the hole transport material of step 9) onto the perovskite film of step 7), spin-coating Spiro-MeOTAD at 3000 revolutions per minute for 30 seconds to form a hole transport layer, and oxidize in air for 24 hours.

[0058] Additional notes:

[0059] Phase transition can be achieved at room temperature, without the need for annealing temperatures above 150°C as in conventional methods. Figure 1 shown.

[0060] As the solution reaction time increases, the black phase FAPbI 3 The XRD peaks of perovskite gradually increase, such as Figure 2 As shown, the RD peak intensity is the strongest after 36 hours.

[0061] In addition, the film after hot spin coating of the reacted solution can be directly transformed into black phase FAPbI at room temperature. 3 Perovskites, such as Figure 3 shown. Figure 3 It is shown that as the reaction time of the precursor solution increases, the film gradually changes from transparent color to black perovskite.

[0062] Step 11) Vacuum evaporation technology is used to evaporate 5nm MoO on the hole transport layer of step 10). 3 Then, 100nm of metal electrode Ag is evaporated to obtain a perovskite solar cell. The device structure is as follows Figure 6 shown.

[0063] Step 12) Under standard test conditions (AM1.5G illumination), the energy conversion efficiency of the battery device prepared in this example is 19.49, the open circuit voltage is 1.127V, and the short circuit current is 22.33mA / cm 2 , the filling factor is 77.47%. Figure 7 shown.

[0064] Example 2

[0065] This example is a method for preparing formamidino FAPbI using the ionic liquid methylamine acetate (MAAc) of the present invention as a solvent in air at low temperature. 3 Inverted planar heterojunction perovskite solar cell, in order to fully understand the present invention. Mainly includes the following steps:

[0066] Step 1) Weigh 281.6 mg of lead iodide and 81.5 mg of iodoformamidine, and dissolve them in 1 ml of MAAc solvent.

[0067] Step 2) The precursor solution prepared in step 1) is reacted at 90° C. for 36 hours, with precise control of temperature and time.

[0068] Step 3) Clean the ITO conductive glass by adding ethanol, ultrapure water, cleaning agent, ultrapure water, acetone, and ethanol in the order of 10 minutes each, and blow dry with nitrogen to obtain a clean conductive glass substrate.

[0069] Step 4) The ITO substrate cleaned in step 2) is treated with ultraviolet ozone for 15 minutes.

[0070] Step 5) Take 10 mg of NiOx and completely disperse it in 1 ml of ultrapure water.

[0071] Step 6) Take 45 μL of the prepared NiOx and drop it onto the ITO substrate treated in step 4), and use a spin coater to spin coat it into a film at a speed of 3000 revolutions per minute for 30 seconds. The ITO spin-coated with NiOx is annealed at 150° C. for 15 minutes.

[0072] Step 7) placing the ITO conductive substrate with the hole transport layer spun on it after annealing in step 6) on a hot spin coater and preheating for 5 minutes.

[0073] Step 8) Take 80 μL of the perovskite precursor solution after the reaction in step 2) and drop it onto the preheated ITO substrate in step 7), spin-coat it into a film, and then anneal it to form a perovskite film. The spin-coating speed of the perovskite precursor solution is 4000 revolutions per minute for 20 seconds, and anneal it in air at 100° C. for 5 minutes.

[0074] Step 9) Weigh 20 mg of PCBM, dissolve it completely in 1 ml of chlorobenzene solvent, and stir to dissolve for 24 hours before use.

[0075] Step 10) Spin-coating the electron transport material of step 9) onto the perovskite film of step 7), spin-coating the PCBM at 1000 revolutions per minute for 30 seconds to form an electron transport layer, and annealing at 100° C. for 5 minutes.

[0076] Step 11) Vacuum evaporation technology is used to evaporate 5nm LiF on the electron transport layer of step 10), and then 100nm metal electrode Ag is evaporated to obtain a perovskite solar cell. The device structure is as follows Figure 8 shown.

[0077] Step 12) Under standard test conditions (AM1.5G illumination), the energy conversion efficiency of the battery device prepared in this example is the best 17.98, the open circuit voltage is 1.124V, and the short circuit current is 21.71mA / cm 2 , the filling factor is 73.69%. Fig. 9 shown.

[0078] The present invention is not limited to the specific technical solutions described in the above embodiments, and all technical solutions formed by equivalent replacement are within the protection scope required by the present invention.

Claims

1. A method for preparing a formamidite-based FAPbI3 perovskite solar cell in a low-temperature one-step process in air, characterized in that: The following steps are involved: (1) dissolving lead iodide and iodoformamidine in a proton-type ionic liquid methylamine acetate solution in a molar ratio of 1:1 to prepare a perovskite precursor solution; (2) The perovskite precursor solution was stirred and reacted at 90 °C for 36 h to achieve ion recombination and construct a pre-perovskite structure; (3) Spin coating the hole or electron transport material onto the ITO or FTO conductive substrate; (4) Spin-coating the prepared perovskite precursor solution on an ITO or FTO conductive substrate with a hole transport layer or an electron transport layer, and annealing at 40-120°C for 5 min to obtain a dense and uniform active layer; (5) Spin coating an electron or hole transport layer on the perovskite layer; (6) Vacuum evaporating a modification layer and a metal electrode on the electron or hole transport layer.

2. The method for preparing a formamidine-based FAPbI3 perovskite solar cell in a low-temperature one-step process in air according to claim 1, characterized in that: The concentration of the perovskite precursor solution in step (1) is 200-600 mg / mL.

3. The method for preparing a formamidine-based FAPbI3 perovskite solar cell in a low-temperature one-step process in air according to claim 1, characterized in that: In the step (3), the hole transport layer spin-coated on the transparent conductive ITO glass is PEDOT:PSS, PTAA or NiOx; the electron transport layer is CPTA, SnO2 or TiO2.

4. The method for preparing a formamidine-based FAPbI3 perovskite solar cell in a low-temperature one-step process in air according to claim 1, characterized in that: The electron transport layer spin-coated on the perovskite layer is PCBM, and the hole transport layer is Spiro-MeOTAD; the specific steps are as follows: PCBM was dissolved in chlorobenzene at a concentration of 18 mg / mL; 72.6 mg / ml Spiro-MeOTAD was dissolved in chlorobenzene and stirred for one hour before adding 17.5 μL of lithium bis(trifluoromethanesulfonimide) dissolved in acetonitrile at a concentration of 520 mg / mL, and finally 29 μL of 4-tert-butylpyridine.

5. The method for preparing a formamidine-based FAPbI3 perovskite solar cell in a low-temperature one-step process in air according to claim 1, characterized in that: The modified layers are LiF and MoO3, respectively, and the metal electrodes are Au, Ag or Al; the specific steps are as follows: LiF was evaporated on the electron transport layer of the inverse structure with a thickness of 2 nm; MoO3 was evaporated on the hole transport layer in the orthogonal structure with a thickness of 5 nm; The thickness of the metal electrode is 100 nm.

6. A perovskite solar cell prepared according to the method for preparing a formamidine-based FAPbI3 perovskite solar cell in a low-temperature one-step process in air according to any one of claims 1 to 5.

7. Application of the method for preparing formamidine-based FAPbI3 perovskite solar cells by a one-step method at low temperature in air according to claim 1 in the field of optoelectronics.

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