A method for preparing a passivated perovskite solar cell

Abstract

A method for preparing a passivated perovskite solar cell belongs to the technical field of perovskite solar cell preparation. The method includes: pretreatment of a substrate, preparation of an electron transport layer, a perovskite film, a passivation layer, a hole transport layer and an electrode. A bifunctional square acid derivative is dissolved in n-butanol and then spin-coated on the perovskite film to prepare a passivation layer. The method converts CsPbIBr 2 The efficiency of perovskite solar cells has increased by 31%, and the humidity stability of the passivated cells has also been significantly improved.

Description

Technical Field

[0001] The invention belongs to the field of perovskite solar cells and provides a perovskite film modification method and a perovskite solar cell preparation process. Background Art

[0002] Perovskite solar cells have attracted more and more attention due to their high absorption coefficient, adjustable band gap and high photoelectric conversion efficiency. For organic perovskites, they are particularly easy to decompose under conditions such as heating and humidity. In contrast, all-inorganic perovskites have higher thermal stability and can be a perfect substitute for organic perovskites. Among all-inorganic perovskites, CsPbIBr 2 Perovskite has a suitable band gap and excellent phase stability, which is gaining more and more attention. However, a large number of defects will be generated in the preparation process of perovskite film. These defects exist inside the perovskite and at the grain boundaries, which seriously restricts the photoelectric efficiency and stability of the device. Therefore, reducing defects in perovskite films has become a hot topic in current research and is one of the obstacles to the commercial development of perovskite solar cells. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the present invention provides a method for preparing a passivated perovskite solar cell, in which a passivation layer of a squaric acid derivative is spin-coated on the surface of the perovskite film to reduce defects in the perovskite film and improve the efficiency of the perovskite solar cell.

[0004] The technical solution adopted by the present invention is: a method for preparing a passivation type perovskite solar cell, comprising the following steps:

[0005] (1) Pretreatment of substrate;

[0006] (2) Preparation of electron transport layer;

[0007] (3) Preparation of precursors;

[0008] (4) Preparation of perovskite thin films;

[0009] (5) Preparation of passivation layer;

[0010] (6) Preparation of hole transport layer;

[0011] (7) Preparation of electrodes.

[0012] The pretreatment of the substrate in step (1) includes: ultrasonically cleaning the FTO substrate for 30 minutes using detergent, deionized water, acetone, and ethanol, respectively. After cleaning, the substrate is dried using a hair dryer, and then treated with ultraviolet light for 30 minutes.

[0013] Step (2) Preparation of the electron transport layer includes SnO2 and TiO 2 One of them.

[0014] The electron transport layer is TiO 2 When bis(2,4-pentanedione)bis(2-propanoate)titanium and ethanol were mixed in a volume ratio of 9:1 to prepare an electron transport material solution;

[0015] The electron transport layer is SnO 2 When the tin dioxide colloid is mixed with water in a volume ratio of 1:5, an electron transport material solution is prepared.

[0016] Step (3) Preparation of the precursor solution includes preparing a perovskite precursor solution using 367 mg PbBr 2 The solution was dissolved in 1 mL of dimethyl sulfoxide (DMSO) and 259 mg of CsI, and stirred at 70 °C overnight for use.

[0017] The hole transport layer precursor was prepared by combining 72.3 mg of Spiro-OMeTAD and additives (17.5 µL Li-TFSI, 30 µL FK209Co(III)TFSI and 28.8 µL t-BP).

[0018] The passivation agent precursor solution was prepared by dissolving 0.3 mg VG1-C8 in 1 mL of n-butanol solution and stirring for 2 hours. The solution was filtered through a 0.45 μm filter head before use.

[0019] Bifunctional square acid derivative VG1-C8(C 44 H 56 N 2 O 6 ), whose structural formula is:

[0020]

[0021] VG1-C8

[0022] The preparation method of step (4) is to first preheat the substrate on a hot plate at 60°C for 5 minutes, then spin-coat the perovskite precursor solution on the substrate, using 1500 rpm for 15 seconds in the first stage and 3500 rpm for 30 seconds in the second stage, and anneal on a hot plate at 225°C for 10 minutes.

[0023] The preparation method described in step (5) is to drop the passivation agent precursor on the perovskite film, then spin-coat it at 3000 rpm for 30 seconds, and finally anneal at 60° C. for 10 minutes.

[0024] The electrode material in step (7) is one of gold and silver.

[0025] The efficiency after passivation with a square acid derivative was 12.10%.

[0026] The beneficial effects of the present invention are:

[0027] The present invention selects a method for post-processing the perovskite film using a passivation layer. This solution reduces the defect state density of the perovskite film and improves the efficiency and stability of the perovskite solar cell. The reason is that a large number of defects will be generated in the perovskite film during the preparation process. These defects exist inside the perovskite and at the grain boundaries, which seriously restrict the photoelectric efficiency and stability of the device. The present invention introduces an efficient square acid derivative as a passivation layer, which has multiple C=O functional groups and can act as a Lewis base to passivate the Pb in the perovskite film. 2+ , thereby reducing defects in the perovskite film and improving the stability of the perovskite solar cell. In addition, the square acid derivatives also have hydrophobic groups that can prevent water from invading the perovskite film, thereby improving the humidity stability of the perovskite solar cell.

[0028] The present invention uses a square acid derivative (VG1-C8) to passivate the perovskite film and form a modified layer on the perovskite film. The introduction of the square acid derivative can passivate the Pb in the perovskite film. 2+ Defects can effectively reduce the defect state density and inhibit non-radiative recombination. In addition, the addition of a passivation layer can also achieve a hydrophobic effect, making CsPbIBr 2 The humidity stability of perovskite solar cells has also been improved.

[0029] The present invention improves the efficiency of the perovskite solar cell by introducing a squaric acid derivative as a passivation layer, the efficiency after passivation is increased from 9.2% to 12.10%, and the humidity stability is also greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the structure of the square acid derivative (VG1-C8) described in Example 1.

[0031] Figure 2 Perovskite cells treated with passivation agent and untreated in Example 1 J-V curve.

[0032] Figure 3 The long-term stability of the passivation agent treated and untreated batteries in Example 1 under 40% relative humidity and 25°C. DETAILED DESCRIPTION

[0033] Example 1

[0034] (1) Pretreatment of the substrate: The substrate was ultrasonically cleaned for 30 minutes using detergent, deionized water, acetone, and ethanol, respectively. After cleaning, it was blown dry with a hair dryer and then treated with ultraviolet light for 30 minutes.

[0035] (2) Preparation of electron transport layer: Titanium (IV) bis(2,4-pentanedione) bis(2-propanoate) and ethanol were mixed in a volume ratio of 9:1, filtered and poured into a spray pot, and evenly sprayed on the FTO substrate by thermal spraying, and then sintered in a flat furnace at 500°C for 30 minutes to obtain a compact titanium oxide layer.

[0036] (3) Preparation of precursor solution: The perovskite precursor solution uses 367 mg PbBr 2 and 259 mg CsI were dissolved in 1 mL of dimethyl sulfoxide (DMSO) and stirred at 70 °C overnight. The hole transport layer precursor was prepared by combining 72.3 mg of Spiro-OMeTAD and additives (17.5 µL Li-TFSI, 30 µL FK209Co(III)TFSI and 28.8 µL t-BP). The passivation agent precursor was prepared by dissolving 0.3 mg of a square acid derivative in 1 mL of n-butanol solution and stirring for 2 hours. Filter with a 0.45 μm filter head before use.

[0037] (4) Preparation of perovskite film: First, the substrate was preheated on a hot plate at 60°C for 5 min, and then the perovskite precursor solution was spin-coated on the substrate at 1500 rpm for 15 s in the first stage and at 3500 rpm for 30 s in the second stage, followed by annealing on a hot plate at 225°C for 10 min.

[0038] (5) Preparation of passivation layer: The passivation agent precursor was dropped onto the perovskite film, followed by spin coating at 3000 rpm for 30 seconds, and finally annealing at 60 °C for 10 minutes.

[0039] (6) Preparation of hole transport layer: The prepared precursor solution was dropped onto the perovskite and then spin coated at 3000 rpm for 30 seconds.

[0040] (7) Preparation of electrode: A layer of silver with a thickness of 100 nm was deposited on the hole transport layer by vacuum evaporation as an electrode.

[0041] Table 1 CsPbIBr passivated with and without squaric acid derivatives 2 Photovoltaic parameters of perovskite solar cells

[0042]

[0043] It can be seen from the table above that the cell efficiency after passivation increased from 9.2% to 12.10%, which is an overall improvement of CsPbIBr 2 The efficiency of perovskite solar cells has increased by 31%.

[0044] Figure 3It is the long-term stability of passivator-treated and untreated batteries under 40% relative humidity and 25°C. After 500h, the efficiency of the perovskite battery treated with the passivator is more than twice that of the perovskite battery not treated with the passivator. The perovskite battery treated with the passivator shows excellent long-term stability.

Claims

1. A method for preparing a passivated perovskite solar cell, characterized in that: The following steps are involved: (1) Pretreatment of the substrate: ultrasonically clean the substrate using detergent, deionized water, acetone, and ethanol; after cleaning, blow dry, and treat with ultraviolet light; (2) Preparation of electron transport layer: Spraying the electron transport material solution onto the substrate by thermal spraying and sintering in a flat furnace to obtain the electron transport layer; (3) Preparation of precursor solution: The perovskite precursor solution is made of PbBr2 and CsI dissolved in dimethyl sulfoxide, where the concentrations of PbBr2 and CsI are 1 mol / L respectively; The hole transport layer precursor solution is prepared with 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene and a mixed additive at a ratio of 0.9-1g:1L, wherein the mixed additive includes bis(trifluoromethane)sulfonyl imide, tris[4-tert-butyl-2-(1H-pyrazol-1-yl)pyridinyl]cobalt tris(1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide salt) and 4-tert-butylpyridine; The passivation agent precursor solution is made of a square acid derivative dissolved in a n-butanol solution, and the concentration of the square acid derivative is 0.3-0.5 g / L; The structure of the square acid derivative is: VG1-C8 (4) Preparation of perovskite film: preheat the substrate on a hot plate at 60°C, then spin-coat the perovskite precursor solution on the substrate and anneal on a hot plate at 200-250°C for 5-15 minutes; (5) Preparation of passivation layer: drop the passivation agent precursor on the perovskite film, spin-coat at 2000-3000 rpm for 30-50 seconds, and finally anneal at 60-80 °C for 5-10 minutes; (6) Preparation of hole transport layer: drop the hole transport layer precursor on the perovskite and spin coat at 2000-3000 rpm for 30-50 seconds; (7) Preparation of electrodes: A layer of gold or silver is deposited on the hole transport layer by vacuum evaporation as an electrode.

2. The method for preparing a passivation-type perovskite solar cell according to claim 1, characterized in that: The passivation agent precursor solution was filtered with a 0.45 μm filter head before use.

3. The method for preparing a passivation-type perovskite solar cell according to claim 1, characterized in that: The spin coating process of the perovskite precursor solution used 1500 rpm for 15 seconds in the first stage and 3500 rpm for 30 seconds in the second stage.

4. The method for preparing a passivation-type perovskite solar cell according to claim 1, characterized in that: The electron transport layer is a SnO2 or TiO2 layer; When the electron transport layer is TiO2, bis(2,4-pentanedione)bis(2-propanoate)titanium and ethanol are mixed in a volume ratio of 9:1 to prepare an electron transport material solution; When the electron transport layer is SnO2, the tin dioxide colloid and water are mixed in a volume ratio of 1:5 to prepare an electron transport material solution.

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