Stabilizer of perovskite solution and perovskite solution capable of being stored for long time

Abstract

The invention provides a stabilizer of a perovskite solution and the perovskite solution capable of being stored for a long time, and aims to solve the problem of stability of a precursor solution in the prior art, the stabilizer is a binary mixed stabilizer, the general formula of the stabilizer can be expressed as (MA) x (B) 1-x (H2PO2) 1-xClx, x is more than 0 and less than 1, MA < + > is methylamine cation, H < 2 + > is methyl amine cation, H < 2 + > is methyl amine cation, and H < 2 + > is methyl amine cation. And B is one or more of aniline cation PA < + >, formamidine cation FA < + >, methylamine cation MA < + >, dimethylamine cation DMA < + > and ammonium cation NH4 < + >. A stabilizer with the concentration of 0.01-0.4 mol / L is added into a precursor solution, colloidal particles are stabilized through interaction with [PbI6] 4, oxidation of iodide ions is inhibited by reducing groups contained in the stabilizer, side reactions are further inhibited, and compared with a newly prepared precursor solution, the perovskite precursor solution stored for 30 days for a long time has the advantages that the stability of the perovskite precursor solution is improved, and the service life of the perovskite precursor solution is prolonged. The crystallinity, the surface appearance and the absorbance of the prepared perovskite thin film are basically unchanged, and the efficiency change of the obtained perovskite solar cell does not exceed 3%.

Description

Technical Field

[0001] The present invention belongs to the field of perovskite optoelectronic devices, and particularly relates to a precursor solution for perovskite that can be stably stored and its application in perovskite solar cells. Background Art

[0002] In recent years, organic-inorganic hybrid perovskite materials have developed rapidly due to their excellent optoelectronic properties and are an active research field in both scientific research and industrial applications, such as applications in optoelectronic materials, sensors, detectors, electronic components, etc. Among them, perovskite solar cells have always been a research hotspot. The power conversion efficiency of certified single-junction perovskite solar cells has exceeded 26%, indicating that this technology has taken a big step towards commercial production. However, due to colloidal aggregation and iodine oxidation, it is very difficult for perovskite precursor solutions to be stably stored for a long time. Fresh solutions need to be prepared before fabricating perovskite devices, otherwise it will lead to deterioration of the performance of the fabricated perovskite solar cells.

[0003] The performance of perovskite solar cells will be significantly attenuated due to the long-term storage of perovskite precursor solutions. On the one hand, it is the physical stability of the precursor solution. The PbI2 colloidal particles in the perovskite precursor solution will be affected by factors such as Brownian motion, van der Waals forces, and surface charges, which will destroy its stability. Among them, Brownian motion is dominant. The irregular random motion of colloidal particles causes them to collide and aggregate, and this aggregation will cause the colloids in the precursor solution to coagulate and break the original dispersed state. On the other hand, it is the chemical stability of the precursor solution. The iodide ions in the perovskite precursor solution are easily oxidized by oxygen in the air to I2 / I3 − , resulting in iodine deficiency in the precursor solution. At the same time, formamidinium cations and methylammonium cations will undergo side reactions to produce by-products such as N-methylformamidine (MFAI) and N,N-dimethylformamidine (DMFAI). The physical / chemical instabilities existing in the perovskite precursor solution will affect the uniform growth and homogeneous crystallization of perovskite thin films, and the prepared perovskite thin films will have more defects, thus affecting the device performance. Solving the stability problem of perovskite precursor solutions not only helps to form high-quality uniform thin films, but is also crucial for actual continuous large-scale industrial production. Summary of the Invention

[0004] The purpose of the present invention is to solve the stability problem of the precursor solution in the prior art and provide a perovskite precursor solution that can be stored for a long time. The present invention solves the above technical problems through the following technical solutions: A perovskite stabilizer, which is a binary mixed stabilizer, and its general formula can be expressed as (MA) x (B) 1-x (H2PO2) 1-x Cl x, 0 < x < 1, where MA + is methylammonium cation, and B is aniline cation (PA + ), formamidinium cation (FA + ), methylammonium cation (MA + ), dimethylammonium cation (DMA + ), ammonium cation (NH4 + ). It should be noted that when x = 0, the stabilizer is insoluble in the perovskite precursor solution ( Figure 11 as shown); when x = 1, the stabilizer does not have the effect of stabilizing the perovskite precursor solution.

[0005] A perovskite precursor solution containing the above stabilizer that can be stored for a long time, and the perovskite precursor solution contains 0.01 - 0.4 mol / L of the stabilizer.

[0006] The storable perovskite precursor solution, and the perovskite precursor components are one or several mixed components of CH3NH3PbI3, HC(NH2)2PbI3, HC(NH2)2PbBr3, CsPbI3, CsPbBr3.

[0007] Further preferably, the organic solvent in the precursor solution is a commonly used solvent in the art, such as one or more of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), ethylene glycol methyl ether (2-ME), γ-butyrolactone (GBL).

[0008] Further preferably, the concentration of the perovskite precursor solution is 0.6 - 2.5 mol / L commonly used in the art.

[0009] The positive and progressive effects of the present invention are as follows: The present invention adds a stabilizer to the precursor solution, and stabilizes the colloidal particles by interacting with [PbI6] 4− . The reducing groups contained therein also inhibit the oxidation of iodide ions, thereby inhibiting the occurrence of side reactions. Compared with the newly prepared precursor solution, the perovskite precursor solution stored for 30 days has basically unchanged crystallinity, surface morphology, and absorbance of the prepared perovskite thin film, and the efficiency change of the obtained perovskite solar cell does not exceed 3%. This is of great significance for realizing the large-scale preparation of perovskite materials with stable performance. Brief Description of the Drawings

[0010] Figure 1 is a schematic diagram of the action mechanism of the long-term storage of the perovskite precursor solution; Figure 2 is a photo of the aged perovskite precursor solution; Figure 3Particle size comparison diagram of perovskite precursor solutions for Comparative Example 1 and Example 1; Figure 4 1H NMR comparison diagram of perovskite precursor solutions for Comparative Example 1 and Example 1; Figure 5 UV-Vis absorption spectrum comparison diagram of perovskite precursor solutions for Comparative Example 1 and Example 2; Figure 6 Scanning electron microscope (SEM) comparison diagram of perovskite thin films for Comparative Example 1 and Example 1; Figure 7 X-ray diffraction (XRD) comparison diagram of perovskite thin films for Comparative Example 1 and Example 3; Figure 8 UV-Vis absorption spectrum comparison diagram of perovskite thin films for Comparative Example 1 and Example 4; Figure 9 SCLC curve comparison diagram of perovskite thin film single-hole devices for Comparative Example 1 and Example 1; Figure 10 Perovskite solar cell performance comparison diagram for Comparative Example 1 and Example 1; Figure 11 For the precursor solution containing (MA) 0.94 (B) 0.06 (H2PO2) 0.06 Cl 0.94 (left) and the precursor solution photo containing BH2PO2 (right). Detailed implementation mode

[0011] The present invention will be further described below by way of examples, but the present invention is not limited to the scope of the described examples.

[0012] Example 1 (1) Dissolve lead iodide, formamidinium iodide, methylammonium iodide, (MA) 0.94 (PA) 0.06 (H2PO2) 0.06 Cl 0.94 in DMF to prepare a perovskite precursor solution with a concentration of 1.1 mol / L. Among them, the molar ratio of lead iodide to the AX site (i.e., formamidinium iodide and methylammonium iodide) is 1:1, the molar ratio of formamidinium iodide to methylammonium iodide is 7:3, and the addition amount of the stabilizer is 0.28 mol / L. Shake it on a shaker to completely dissolve it and filter it with a 0.22 μm filter membrane to obtain the precursor solution used in Example 1, and the components are FA 0.7 MA 0.3 PbI3. The fresh solution is placed in air for 30 days to obtain the aged solution in Example 1. The optical photos of the solution at different aging times are as Figure 2 shown.

[0013] (2) The ITO glass substrate was ultrasonically cleaned and dried with N2, then the substrate was treated with ultraviolet ozone for 15 min, and then an ethanol solution of Meo-2PACz at 0.5 mg / mL was coated on it. After annealing at 100 °C for 10 min, the above precursor solution was coated by the doctor blade method. The slit of the doctor blade was 55 μm, and the coating speed was 30 mm / s. After annealing at 110 °C for 10 min, a perovskite thin film was obtained. Finally, a 25 nm thick C 60 , a 7.5 nm thick BCP, and an 80 nm thick Cu perovskite solar cell device were deposited by a vacuum coater.

[0014] Example 2 Lead iodide, formamidinium iodide, cesium iodide, (MA) 0.94 (FA) 0.06 (H2PO2) 0.06 Cl 0.94 were dissolved in DMF to prepare a perovskite precursor solution with a concentration of 1.1 mol / L. Among them, the molar ratio of lead iodide to the AX site (formamidinium iodide and cesium iodide) was 1:1, the molar ratio of formamidinium iodide to cesium iodide was 9:1, and the addition amount of the stabilizer was 0.28 mol / L. It was shaken on a shaker to completely dissolve and filtered through a 0.22 μm filter membrane to obtain the precursor solution used in Example 2, with the composition of FA 0.9 Cs 0.1 PbI3. The aged solution in Example 2 was obtained after the fresh solution was placed in air for 30 days. Optical photos of the solution at different aging times are as Figure 2 shown.

[0015] Example 3 Lead iodide, formamidinium iodide, methylammonium iodide, cesium iodide, MA(H2PO2) 0.06 Cl 0.94 were mixed and dissolved in DMF to prepare a perovskite precursor solution with a concentration of 1.1 mol / L. Among them, the molar ratio of lead iodide to the AX site (i.e., formamidinium iodide, methylammonium iodide, and cesium iodide) was 1:1, the molar ratio of formamidinium iodide, methylammonium iodide, and cesium iodide was 0.85:1:0.05, and the addition amount of the stabilizer was 0.28 mol / L. It was shaken on a shaker to completely dissolve and filtered through a 0.22 μm filter membrane to obtain the precursor solution used in Example 3, with the composition of FA 0.85 MA 0.1 Cs 0.05 PbI3. The aged solution in Example 3 was obtained after the fresh solution was placed in air for 30 days. Optical photos of the solution at different aging times are as Figure 2 shown.

[0016] Example 4 Lead iodide, formamidinium iodide, (MA)0.94 (DMA) 0.06 (H2PO2) 0.06 Cl 0.94 Mix and dissolve them in DMF to prepare a perovskite precursor solution with a concentration of 1.1 mol / L. Among them, the molar ratio of lead iodide to formamidinium iodide is 1:1, the addition amount of the stabilizer is 0.28 mol / L. Shake it on a shaker until completely dissolved and filter it with a 0.22 μm filter membrane to obtain the precursor solution used in Example 4, and the component is FAPbI3. The aged solution in Example 4 is obtained after the fresh solution is placed in the air for 30 days. The optical photos of the solution at different aging times are as Figure 2 shown.

[0017] Example 5 Mix lead iodide, formamidinium iodide, methylammonium iodide, (MA) 0.94 (NH4) 0.06 (H2PO2) 0.06 Cl 0.94 Mix and dissolve them in DMF to prepare a perovskite precursor solution with a concentration of 1.1 mol / L. Among them, the molar ratio of lead iodide to the AX site (i.e., formamidinium iodide and methylammonium iodide) is 1:1, the molar ratio of formamidinium iodide to methylammonium iodide is 3:7, the addition amount of the stabilizer is 0.28 mol / L. Shake it on a shaker until completely dissolved and filter it with a 0.22 μm filter membrane to obtain the precursor solution used in Example 5, and the component is FA 0.3 MA 0.7 PbI3. The aged solution in Example 5 is obtained after the fresh solution is placed in the air for 30 days.

[0018] Comparative Example 1 Mix lead iodide, formamidinium iodide, methylammonium iodide, and MACl in DMF to prepare a perovskite precursor solution with a concentration of 1.1 mol / L. Among them, the molar ratio of lead iodide to the AX site (i.e., formamidinium iodide and methylammonium iodide) is 1:1, the molar ratio of formamidinium iodide to methylammonium iodide is 7:3. Shake it on a shaker until completely dissolved and filter it with a 0.22 μm filter membrane to obtain the precursor solution used in Comparative Example 1, and the component is FA 0.7 MA 0.3 PbI3. The aged solution in Comparative Example 1 is obtained after the fresh solution is placed in the air for 30 days.

[0019] Using the same method, prepare perovskite precursor solutions with components of FA 0.9 Cs 0.1 PbI3, FA 0.85 MA 0.1 Cs 0.05 PbI3 and FAPbI3. The aged solutions of the corresponding components are obtained after the fresh solutions are placed in the air for 30 days. The optical photos of the solution at different aging times are as Figure 2As shown. The remaining operations are the same as those in Example 1.

[0020] Effect Example 1 Comparison of the properties of the aging solution in Example 1 with the aging solution of the same components in Comparative Example 1.

[0021] (1)Comparison of the particle sizes of the solution before and after aging The size and distribution of the colloid in the solution before and after aging for 30 days were compared through dynamic light scattering (DLC) testing. It can be seen that the particle distribution in the perovskite precursor solution in Example 1 was concentrated around 1.64 nm, and about 9% of the particles were distributed around 1.75 µm. After the solution was aged for 30 days, the size and distribution of the colloid remained basically stable. The size distribution of the colloid was all concentrated around 1.55 nm, and there was no aggregation of large-sized colloids, indicating that the addition of Figure 3 (MA) 0.94 (PA) 0.06 (H2PO2) 0.06 Cl 0.94 not only stabilized the state of the solution, but also dispersed large-sized colloid particles into small-sized particles, making the size distribution of the colloid particles more uniform and concentrated. After the solution of the same components in Comparative Example 1 was aged for 30 days, the distribution of the colloid particles shifted towards larger sizes.

[0022] (2)Comparison of the nuclear magnetic resonance before and after solution aging The side reaction situation after the solution was aged for 30 days was compared through nuclear magnetic resonance hydrogen spectrum ( 1 1H NMR) testing. It can be seen that there was no side reaction in the perovskite precursor solution in Example 1 after aging for 30 days; while nitrogen-nitrodimethyliodomethylformamidine and nitrogen-methyliodomethylformamidine were produced in the solution of the same components in Comparative Example 1 after aging for 30 days. It shows that this method inhibits side reactions in the solution. Figure 4

[0023] (3)Comparison of the ultraviolet-visible absorption spectra before and after solution aging The formation of I2 / I3 in the solution after the solution was aged for 30 days was compared through ultraviolet-visible (UV-Vis) absorption spectrum measurement. It can be seen from − that there was no significant change in the absorption band edge of the perovskite precursor solution in Example 2 before and after aging for 30 days, while I2 / I3 Figure 5 was produced in the perovskite aging solution of the same components in Comparative Example 1. −

[0024] Effect Example 2 Comparison of the properties of the perovskite films prepared from the aging solution in Example 1 and the aging solution of the same components in Comparative Example 1.

[0025] (1)Comparison of the surface morphologies of the films prepared before and after solution aging The surface morphology of the perovskite film was characterized by scanning electron microscopy (SEM). As Figure 6 shown, there was basically no difference in the surface grain size and quality of the perovskite films prepared from the aged solution and the fresh solution in Example 1; while in Comparative Example 1, the grains of the perovskite film prepared from the same-component aged solution were much smaller than those of the perovskite film prepared from the fresh solution.

[0026] (2) Comparison of the crystallinity of the films prepared before and after solution aging The crystallinity of the perovskite film was characterized by X-ray diffraction (XRD). As Figure 7 shown, the crystallinity and the preferred orientation of the crystals of the perovskite films prepared from the aged solution and the fresh solution in Example 3 were basically unchanged; while in Comparative Example 1, the crystallization intensity of the perovskite film prepared from the same-component aged solution was weaker than that of the perovskite film prepared from the fresh solution, and the perovskite δ phase appeared.

[0027] (3) Comparison of the optical absorbance of the films prepared before and after solution aging The optical absorbance of the perovskite film was characterized by ultraviolet-visible (UV-Vis) absorption spectroscopy. As Figure 8 shown, there was basically no change in the absorption edge and absorption intensity of the perovskite films prepared from the aged solution and the fresh solution in Example 4; while in Comparative Example 1, the absorption intensity of the perovskite film prepared from the same-component aged solution decreased in the range of 550 - 750 nm compared with that of the perovskite film prepared from the fresh solution, and the absorption edge changed.

[0028] Effect Example 3 The internal defect density of the perovskite film was measured by the space-charge-limited current (SCLC) method. As Figure 9 shown, by calculating, the hole defect density of the single-hole device prepared from the aged perovskite precursor solution in Example 1 was 4.966×10 15 cm −3 , while the hole defect density of the single-hole device prepared from the same-component aged perovskite precursor solution in Comparative Example 1 was: 1.269×10 16 cm −3 . It can be compared that the perovskite film prepared from the aged perovskite precursor solution containing (MA) 0.94 (PA) 0.06 (H2PO2) 0.06 Cl 0.94 had a lower defect density. It was proved that the perovskite precursor solution containing this stabilizer could be stored stably without affecting the subsequent preparation of the perovskite film. Compared with the newly prepared precursor solution, the state of the perovskite precursor solution after 30 days of long-term storage was basically maintained stable. AsFigure 10 As shown, the efficiency change of the prepared perovskite solar cells does not exceed 3%, which is of great significance for the large-scale preparation of perovskite materials with stable performance.

Claims

1. A perovskite stabilizer, characterized in that, The stabilizer is a binary mixed stabilizer, and its general formula can be expressed as (MA) x (B) 1-x (H2PO2) 1-x Cl x , 0 < x < 1, where MA + is the methylamine cation, and B is one or more of the aniline cation PA + , the formamidine cation FA + , the methylamine cation MA + , the dimethylamine cation DMA + and the ammonium cation NH4 + in one or more of them.

2. A perovskite precursor solution containing the stabilizer described in claim 1, characterized in that, The perovskite precursor solution contains 0.01 - 0.4 mol / L of a stabilizer.

3. The perovskite precursor solution capable of long-term storage according to claim 2, wherein, The perovskite precursor components are one or a mixture of several components selected from CH3NH3PbI3, HC(NH2)2PbI3, HC(NH2)2PbBr3, CsPbI3, and CsPbBr3.

4. The perovskite precursor solution capable of long-term storage according to claim 2, wherein, The organic solvent in the precursor solution is one or more of N,N-dimethylformamide, dimethyl sulfoxide, ethylene glycol methyl ether, and γ-butyrolactone.

5. The perovskite precursor solution capable of long-term storage according to claim 2, wherein, The concentration of the perovskite precursor solution is 0.6 - 2.5 mol / L.

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