Perovskite precursor solution containing iodine bromide

Abstract

The invention belongs to the technical field of solar cells, and particularly relates to a perovskite precursor solution containing iodine bromide. The solution is prepared by dissolving cesium iodide, lead iodide, formamidine iodide, lead bromide, formamidine bromide and iodine bromide in a mixed organic solvent. The iodine bromide can inhibit aging and deterioration of perovskite precursor solution components, and the solution stability is good.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cells, and in particular relates to a perovskite precursor solution containing iodine bromide. Background Art

[0002] Perovskite solar cells are multi-layer thin-film cells. The core perovskite light absorption layer material has the advantages of high absorption coefficient, long carrier lifetime, low defect state concentration, low exciton binding energy, and low-cost solution preparation, making it the forefront of photovoltaic research. However, the solution preparation of perovskite solar cells faces a huge challenge, that is, the perovskite precursor solution is unstable at room temperature, and the unstable state of the perovskite precursor solution is an important factor that reduces the quality of the film and the photovoltaic performance of the solar cell.

[0003] The preparation method of the perovskite precursor solution is as follows: lead halide salts (such as PbI2, PbBr2, PbCl2, etc.) are dissolved in an organic solvent (such as N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), γ-butyrolactone (GBL), etc.) at the same time, and stirred thoroughly to form a variety of ions (methylamine (MA + ), formamidine (FA + ), I - Br - , Cl - , Pb 2+ ) coexist in a perovskite precursor solution. Under room temperature conditions, over time, these ionic groups will interact adversely with each other, such as changes in colloid size, changes in the intermediate phase, and degradation of chemical composition, causing the perovskite precursor solution to deviate from the ideal stoichiometric ratio, thereby affecting the perovskite film morphology, grain size, crystallinity, phase purity, and defect state density, and ultimately reducing the reproducibility and stability of solar cells. Therefore, developing a stabilizer to stabilize the perovskite precursor solution is crucial for the preparation of repeatable, efficient, and stable perovskite solar cells. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the deficiencies of the prior art, the present invention provides a perovskite precursor solution containing iodine bromide, wherein the iodine bromide can inhibit the aging and deterioration of the components of the perovskite precursor solution, and the solution has good stability.

[0005] The technical solution adopted by the present invention to solve the technical problem is as follows: a perovskite precursor solution containing iodine bromide is prepared by dissolving cesium iodide, lead iodide, formamidine iodine, lead bromide, formamidine bromide and iodine bromide in a mixed organic solvent.

[0006] Furthermore, the mixed organic solvent is a mixture of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1.

[0007] Furthermore, the concentration of cesium iodide is 0.12M, the concentration of lead iodide is 1.395M, the concentration of formamidinium iodine is 1.275M, the concentration of lead bromide is 0.105M, the concentration of formamidinium bromide is 0.105M, and the concentration of iodine bromide is 0.09M.

[0008] The beneficial effects of the present invention are as follows: the present invention provides a perovskite precursor solution containing iodine bromide, wherein the iodine bromide in the system can effectively inhibit the transformation of primary amine ions in the perovskite precursor solution into secondary amine ions, thereby reducing the occurrence of deprotonation, and can inhibit the oxidation of halogen anions, thereby improving the solution stability, prolonging the shelf life of the perovskite precursor solution, and effectively avoiding the phenomenon that the actual composition of the solution deviates from the ideal stoichiometric ratio; the solution has good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

[0010] Figure 1 This is a comparison of the H-NMR spectra of the blank perovskite precursor solution after aging and the solid raw material;

[0011] Figure 2 This is the XPS detection image of the blank perovskite precursor solution at 0 days;

[0012] Figure 3 This is the XPS test image of the blank perovskite precursor solution after 14 days of storage;

[0013] Figure 4 This is the NMR hydrogen spectrum of the solution aging of the experimental group's perovskite precursor solution after 14 days. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0015] Example

[0016] The present application claims protection for a perovskite precursor solution containing iodine bromide, which is prepared as follows (hereinafter referred to as the experimental group): N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) are mixed in a volume ratio of 4:1 to form a mixed organic solvent; calculated amounts of cesium iodide (CsI), lead iodide (PbI2), formamidine iodine (FAI), lead bromide (PbBr2), and formamidine bromide (FABr) are added to the system to form a perovskite precursor solution of 0.12M CsI, 1.395M PbI2, 1.275M FAI, 0.105M PbBr2, and 0.105M FABr; and 0.09M iodine bromide (IBr) is continued to be added to the system.

[0017] In order to verify the effect of iodine bromide in the perovskite precursor solution, a blank perovskite precursor solution was prepared, and its preparation method was as follows (hereinafter referred to as the blank example): N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) were mixed in a volume ratio of 4:1 to form a mixed organic solvent; calculated amounts of cesium iodide (CsI), lead iodide (PbI2), formamidine iodine (FAI), lead bromide (PbBr2), and formamidine bromide (FABr) were added to the system to form a perovskite precursor solution of 0.12M CsI, 1.395M PbI2, 1.275M FAI, 0.105M PbBr2, and 0.105M FABr.

[0018] The two perovskite precursor solutions in the experimental group and the blank were subjected to aging experiments at different times. 1 H-NMR and X-ray photoelectron spectroscopy (XPS) were used to qualitatively test the components in the solution and analyze the differences before and after aging.

[0019] Figure 1 After aging the blank solution, verify with the solid test. Figure 2-Figure 3 To verify the aging mechanism of the blank solution, Figure 4 The experimental group and the blank case were placed under the same conditions for 14 days and then the aging test was verified by nuclear magnetic hydrogen spectrum. The results are analyzed as follows:

[0020] from Figure 1 It can be seen that after being placed and aged, the FAI / FABr mixed perovskite precursor solution has a significant imino (=NH) signal peak at 9.0 ppm, containing I - and Br - The deprotonation effect of the multi-halogen ion mixed perovskite precursor solution is strong and the mixed solution ages seriously.

[0021] XPS detection was performed on the blank perovskite precursor solution. Figure 2 , Figure 3 It can be seen that Figure 2The fresh FAI / FABr perovskite precursor solution contains only I - and Br - ,and Figure 3 By tracking the changes in halide ions in the FAI / FABr mixed solution in a solution that had been placed in the water for 14 days, it was found that not only I2 and Br2 were detected, but also trace amounts of +1 iodine cations (I + ), further verifying that the solution had aged and deteriorated.

[0022] Since iodine bromide has been added to the perovskite precursor solution in the experimental group, the system must contain bromide ions, iodine ions, bromine element or iodine element during XPS detection, so no detection is performed. Figure 4 It shows that after the experimental group was placed for 14 days, the nuclear magnetic resonance hydrogen spectrum was used to verify the aging test. After iodine bromide was added to the FAI / FABr mixed solution, after the aging time was the same as the blank case, the nuclear magnetic resonance detection found that no imino group (=NH) signal peak was generated, which means that the perovskite precursor solution of the experimental group did not age, that is, the perovskite precursor solution containing iodine bromide can exist more stably than the perovskite precursor solution without iodine bromide.

[0023] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of this invention patent through the above description. The technical scope of this invention patent is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A perovskite precursor solution containing iodine bromide, characterized in that: It is prepared by dissolving cesium iodide, lead iodide, formamidinium iodide, lead bromide, formamidinium bromide and iodine bromide in a mixed organic solvent.

2. The perovskite precursor solution containing iodine bromide according to claim 1, characterized in that: The mixed organic solvent is a mixture of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:

1.

3. The perovskite precursor solution containing iodine bromide according to claim 1, characterized in that: The concentration of cesium iodide is 0.12M, the concentration of lead iodide is 1.395M, the concentration of formamidinium iodide is 1.275M, the concentration of lead bromide is 0.105M, the concentration of formamidinium bromide is 0.105M, and the concentration of iodine bromide is 0.09M.

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