Perovskite solar cell based on ammonium iodide modified double-layer electron transport layer and acetone doped lead iodide precursor and preparation method thereof

Abstract

A perovskite solar cell based on ammonium iodide modified double-layer SnO2 electron transport layer and acetone doped lead iodide precursor and a preparation method thereof belong to the technical field of perovskite solar cells. The perovskite solar cell is composed of an ITO conductive glass substrate, an ammonium iodide modified double-layer SnO2 electron transport layer, an acetone doped lead iodide precursor perovskite active layer, a phenethylammonium iodide surface passivation layer, a spiro-OMeTAD hole transport layer and a silver electrode in sequence. In the application, the double-layer SnO2 electron transport layer is modified by ammonium iodide to promote the extraction and transmission of electrons, inhibit the hysteresis phenomenon caused by the accumulation of charges at the interface and enhance the conductivity. In addition, the acetone with low dielectric constant is doped in the lead iodide precursor solution in the application, so that the lead iodide film has abundant pores, the defect density of the perovskite layer is reduced, a high-quality film is formed, stable and good carrier transmission is realized, and the performance of the perovskite solar cell is improved.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, specifically relating to a perovskite solar cell based on an ammonium iodide-modified double-layer SnO2 electron transport layer and an acetone-doped lead iodide precursor, and its preparation method. Background Technology

[0002] Perovskite solar cells possess excellent properties such as high absorption coefficient, high carrier mobility, long carrier lifetime, bipolar transport, and solution-based fabrication. Their low fabrication cost and high efficiency have made them a new research hotspot. Solvent engineering has been widely applied to improve the performance of perovskite thin films, and it is mainly divided into one-step and two-step methods. The one-step method involves preparing a precursor solution by mixing a lead salt precursor and an organic halide in a specific stoichiometric ratio, then directly spin-coating it onto a substrate, followed by annealing. This method produces perovskite layers with poor controllability, small grain size, incomplete coverage, and some pinholes. However, the two-step method offers better morphology controllability and crystallization reproducibility, involving the sequential deposition of two precursors. First, lead iodide is coated onto the substrate to form a flat film, which is then further transformed into a perovskite layer after exposure to an organic halide solution. However, in the two-step method, the morphology of the lead iodide film has a great influence on the diffusion of organic halides into perovskite. Often, the reaction of the upper lead iodide to form perovskite will hinder the penetration and diffusion of organic halides. The incomplete conversion of lead iodide will affect charge transport and thus reduce the performance of perovskite solar cells. Summary of the Invention

[0003] The purpose of this invention is to provide a perovskite solar cell based on an ammonium iodide-modified double-layer SnO2 electron transport layer and an acetone-doped lead iodide precursor, and its preparation method.

[0004] The present invention discloses a perovskite solar cell based on an ammonium iodide-modified double-layer SnO2 electron transport layer and an acetone-doped lead iodide precursor. From bottom to top, it consists of an ITO conductive glass substrate, an ammonium iodide-modified double-layer SnO2 (tin dioxide, Alfa Aisa) electron transport layer, a perovskite active layer prepared by an acetone-doped lead iodide (PbI2, Xi'an Baolai) precursor, a phenylethyl ammonium iodide (PEAI, Xi'an Baolai) surface passivation layer, a 2,2",7,7"-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (spiro-OMeTAD, Xi'an Baolai) hole transport layer, and a silver (Ag) electrode. The thickness of the perovskite active layer is 0.8–1.2 μm, the thickness of the ammonium iodide-modified double SnO2 electron transport layer is 20–40 nm, the thickness of the spiro-OMeTAD hole transport layer is 200–300 nm, the thickness of the phenylethyl ammonium iodide surface passivation layer is negligible, and the thickness of the Ag electrode is 80–100 nm.

[0005] The present invention discloses a method for fabricating a perovskite solar cell based on an ammonium iodide double electron transport layer and an acetone-doped lead iodide precursor, the steps of which are as follows:

[0006] 1) Substrate cleaning

[0007] The ITO conductive glass substrate was ultrasonically cleaned with acetone, ethanol and deionized water for 10-20 minutes respectively, and then dried with nitrogen.

[0008] 2) Preparation of SnO2 electron transport layer

[0009] A commercially available SnO2 aqueous dispersion with a mass concentration of 15% was added to deionized water at a volume ratio of 1:3 to 8 to obtain a diluted SnO2 aqueous dispersion. The diluted SnO2 aqueous dispersion was then spin-coated onto a cleaned ITO conductive glass substrate at a speed of 3000 to 6000 rpm for 20 to 40 seconds, and then annealed at 140 to 180°C for 10 to 30 minutes to obtain a SnO2 electron transport layer with a thickness of 10 to 20 nm on the ITO conductive glass substrate.

[0010] Ammonium iodide was dissolved in the diluted SnO2 aqueous dispersion to prepare an ammonium iodide solution with a concentration of 0.5–2 mg / mL. The ammonium iodide solution was then spin-coated onto the SnO2 electron transport layer at a speed of 3000–6000 rpm for 20–40 s, and then annealed at 140–180 °C for 10–30 min to obtain an ammonium iodide-modified SnO2 electron transport layer with a thickness of 10–20 nm. The SnO2 electron transport layer and the ammonium iodide-modified SnO2 electron transport layer are collectively referred to as an ammonium iodide-modified bilayer SnO2 electron transport layer with a thickness of 20 nm–40 nm.

[0011] 3) Preparation of the perovskite active layer

[0012] Preparation of active layer solution

[0013] 645.4–737.6 mg of lead iodide was dissolved in 1 mL of a mixed solvent containing N,N-dimethylformamide (DMF, Beijing Bailingwei) and dimethyl sulfoxide (DMSO, Beijing Bailingwei) in a volume ratio of 9:1. Then, 1–20 μL of acetone (0.1–2% by volume) was added to the mixed solvent, and the mixture was stirred at 500–700 rpm for 15–20 h to obtain a lead iodide solution. 90 mg of formamidinium hydroiodate (FAI, Xi'an Baolait), 6.39 mg of methylammonium iodide (MAI, Xi'an Baolait), and 9 mg of methylammonium chloride (MACl, Xi'an Baolait) were dissolved in 1 mL of isopropanol (IPA, Beijing Bailingwei), and the mixture was stirred at 500–700 rpm for 15–20 h to obtain an organic mixture solution.

[0014] b. Preparation of the perovskite active layer

[0015] Lead iodide solution was spin-coated onto an ammonium iodide-modified SnO2 electron transport layer at 1800–2200 rpm for 20–30 s, and then annealed at 65–75 °C for 1–3 min to obtain a lead iodide film. Then, 60–120 μL of an organic mixture solution was spin-coated onto the lead iodide film at 1800–2200 rpm for 25–35 s, and then annealed at 140–180 °C for 20–40 min to obtain a perovskite active layer with a thickness of 0.8–1.2 μm.

[0016] 4) Preparation of the passivation layer on the surface of phenylethyl ammonium iodide

[0017] 2–4 mg of phenylethyl ammonium iodide was dissolved in 1 mL of isopropanol and stirred at 500–700 rpm for 15–20 h to obtain a phenylethyl ammonium iodide solution. The phenylethyl ammonium iodide solution was spin-coated onto the perovskite active layer at a speed of 3000–5000 rpm for 30–40 s to prepare a phenylethyl ammonium iodide surface passivation layer with negligible thickness.

[0018] 5) Fabrication of the spiro-OMeTAD hole transport layer

[0019] Preparation of hole transport layer solution

[0020] 72.3 mg of spiro-OMeTAD was dissolved in 1 mL of chlorobenzene and stirred at 500–700 rpm for 1–2 h to obtain the original spiro-OMeTAD solution; 520 mg of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, Aladdin) was dissolved in 1 mL of acetonitrile (ACN, Beijing Bailingwei) and stirred at 500–700 rpm for 1–2 h to obtain the acetonitrile solution of LiTFSI; 17.6 μL of the acetonitrile solution of LiTFSI and 28.5 μL of the 4-tert-butylpyridine (TBP, Aladdin) solution were added to the original spiro-OMeTAD solution and stirred at 500–700 rpm for 10–15 h to obtain the hole transport layer solution;

[0021] b. Preparation of the hole transport layer

[0022] The hole transport layer solution was spin-coated onto the passivation layer of phenylethyl ammonium iodide at a rotation speed of 3500-4500 rpm for 20-30 s to prepare a spiro-OMeTAD hole transport layer with a thickness of 200-300 nm.

[0023] 6) Ag electrode preparation

[0024] At a pressure of 1×10 -4 ~1×10-3 Under Pa conditions, Ag electrodes with a thickness of 80–100 nm were deposited on the spiro-OMeTAD hole transport layer at a growth rate of [missing information]. Thus, the perovskite solar cell based on ammonium iodide double electron transport layer and acetone-doped lead iodide precursor described in this invention is obtained.

[0025] In this invention, ammonium iodide is used to modify the double-layer SnO2 electron transport layer, promoting electron extraction and transport, suppressing the hysteresis phenomenon caused by charge accumulation at the interface, and enhancing conductivity. Furthermore, this invention incorporates acetone, which has a low dielectric constant, into the lead iodide precursor solution, causing a change in the charge distribution of the S=O groups in DMSO. The electron cloud density shifts from oxygen to sulfur, enhancing the stability of the S=O groups. This reduces the number of Lewis acid-base adducts formed by the coordination of DMSO with Pb, resulting in abundant pores in the lead iodide film. This facilitates a more complete reaction with the organic halide in the second step, reduces the defect density of the perovskite layer, forms a high-quality film, achieves stable and good carrier transport, and thus improves the performance of the perovskite solar cell. Attached Figure Description

[0026] Figure 1 : Schematic diagram of a perovskite solar cell based on an ammonium iodide double electron transport layer and an acetone-doped lead iodide precursor;

[0027] like Figure 1 As shown, 1 is an ITO conductive glass substrate, 2 is an ammonium iodide-modified double-layer SnO2 electron transport layer, 3 is a perovskite active layer and a phenylethyl ammonium iodide surface passivation layer (the thickness of the phenylethyl ammonium iodide surface passivation layer is negligible), 4 is a spiro-OMeTAD hole transport layer, and 5 is an Ag electrode.

[0028] Figure 2 The current density-voltage characteristic curves (curve A) of the perovskite solar cell based on ammonium iodide-modified double-layer SnO2 electron transport layer and acetone-doped lead iodide precursor described in this invention are compared with those of the traditional perovskite solar cell based on single-layer SnO2 electron transport layer and without acetone-doped lead iodide precursor.

[0029] like Figure 2 As shown, at 100mw / cm 2 The current density-voltage characteristic curve of the cell was measured under the illumination of a solar simulator. The curves were compared with those of a traditional perovskite solar cell (open-circuit voltage (Voc) of 1.095V and short-circuit current density (Jsc) of 24.01mA / cm²). 2Compared to the device with a fill factor (FF) of 75.02% and a power conversion efficiency (PCE) of 19.72%, the device prepared in Example 1 of this invention has a PCE of 22.07%, a Voc of 1.126V, and a Jsc of 24.84mA / cm². 2 The FF is 78.9%, and the device performance is greatly improved. Detailed Implementation

[0030] Example 1

[0031] 1) Substrate cleaning

[0032] The ITO conductive glass substrate was ultrasonically cleaned with acetone, ethanol and deionized water for 15 min each, and then dried with nitrogen.

[0033] 2) Preparation of SnO2 electron transport layer

[0034] A commercially available SnO2 aqueous dispersion with a mass concentration of 15% was added to deionized water at a volume ratio of 1:6 to obtain a diluted SnO2 aqueous dispersion. The diluted SnO2 aqueous dispersion was then spin-coated onto a cleaned ITO conductive glass substrate at a speed of 5000 rpm for 30 s, and then annealed at 150 °C for 20 min to obtain a SnO2 electron transport layer with a thickness of 15 nm on the ITO conductive glass substrate.

[0035] Ammonium iodide was dissolved in the diluted SnO2 aqueous dispersion to prepare an ammonium iodide solution with a concentration of 1 mg / mL. The ammonium iodide solution was spin-coated onto the SnO2 electron transport layer at 5000 rpm for 30 s, and then annealed at 150 °C for 20 min to obtain an ammonium iodide-modified SnO2 electron transport layer with a thickness of 15 nm. The SnO2 electron transport layer and the ammonium iodide-modified SnO2 electron transport layer are collectively referred to as the ammonium iodide-modified bilayer SnO2 electron transport layer, with a total thickness of 30 nm.

[0036] 3) Preparation of the perovskite active layer

[0037] Preparation of active layer solution

[0038] 691.5 mg of lead iodide was dissolved in a 1 mL mixture of DMF and DMSO (9:1 volume ratio), and 10 μL of acetone (1% volume fraction) was added to the mixture. The mixture was then stirred at 600 rpm for 18 h to obtain a lead iodide solution. 90 mg of formamidinium hydroiodate, 6.39 mg of methylammonium iodide, and 9 mg of methylammonium chloride were dissolved in 1 mL of isopropanol and stirred at 600 rpm for 18 h to obtain an organic mixture solution.

[0039] b. Preparation of the perovskite active layer

[0040] Lead iodide solution was spin-coated onto the SnO2 electron transport layer at 2000 rpm for 30 s, and then annealed at 70 °C for 1 min to obtain a lead iodide film; subsequently, 100 μL of organic mixture solution was spin-coated onto the lead iodide film at 2000 rpm for 30 s, and then annealed at 150 °C for 30 min to form a perovskite active layer with a thickness of 1 μm.

[0041] 4) Preparation of the passivation layer on the surface of phenylethyl ammonium iodide

[0042] 3 mg of phenylethyl ammonium iodide was dissolved in 1 mL of isopropanol and stirred at 600 rpm for 18 h to obtain a phenylethyl ammonium iodide solution. The phenylethyl ammonium iodide solution was dynamically spin-coated on the perovskite active layer at 4000 rpm for 30 s to prepare a phenylethyl ammonium iodide surface passivation layer with negligible thickness.

[0043] 5) Fabrication of the spiro-OMeTAD hole transport layer

[0044] Preparation of hole transport layer solution

[0045] 72.3 mg of spiro-OMeTAD was dissolved in 1 mL of chlorobenzene and stirred at 600 rpm for 1 h to obtain the original spiro-OMeTAD solution; 520 mg of LiTFSI was dissolved in 1 mL of acetonitrile and stirred at 600 rpm for 1 h to obtain the LiTFSI acetonitrile solution; 17.6 μL of the LiTFSI acetonitrile solution and 28.5 μL of TBP solution were added to the original spiro-OMeTAD solution and stirred at 600 rpm for 12 h to obtain the hole transport layer solution;

[0046] b. Preparation of the hole transport layer

[0047] A hole transport layer solution was spin-coated onto the passivation layer on the surface of phenylethyl ammonium iodide at a speed of 4000 rpm for 30 s to prepare a spiro-OMeTAD hole transport layer with a thickness of 200 nm.

[0048] 6) Preparation of Ag electrode

[0049] At a pressure of 8×10 -4 Under Pa conditions, Ag electrodes with a thickness of 100 nm were deposited on the spiro-OMeTAD hole transport layer at a growth rate of [missing value]. Thus, the perovskite solar cell fabricated based on ammonium iodide-modified double-layer SnO2 electron transport layer and acetone-doped lead iodide precursor solution described in this invention is obtained.

Claims

1. A method for fabricating a perovskite solar cell based on an ammonium iodide double electron transport layer and an acetone-doped lead iodide precursor, comprising the following steps: 1) Substrate cleaning The ITO conductive glass substrate was ultrasonically cleaned with acetone, ethanol and deionized water for 10-20 minutes respectively, and then dried with nitrogen. 2) Preparation of SnO2 electron transport layer A 15% SnO2 aqueous dispersion was added to deionized water at a volume ratio of 1:3 to 8 to obtain a diluted SnO2 aqueous dispersion. The diluted SnO2 aqueous dispersion was then spin-coated onto a cleaned ITO conductive glass substrate and annealed at 140 to 180°C for 10 to 30 minutes to obtain a SnO2 electron transport layer on the ITO conductive glass substrate. Ammonium iodide was dissolved in the above-mentioned diluted SnO2 aqueous dispersion to prepare an ammonium iodide solution with a concentration of 0.5-2 mg / mL; then the ammonium iodide solution was spin-coated onto the SnO2 electron transport layer, and then annealed at 140-180℃ for 10-30 min to obtain an ammonium iodide-modified SnO2 electron transport layer; the SnO2 electron transport layer and the ammonium iodide-modified SnO2 electron transport layer are collectively referred to as an ammonium iodide-modified bilayer SnO2 electron transport layer; 3) Preparation of the perovskite active layer Preparation of active layer solution 645.4–737.6 mg of lead iodide was dissolved in 1 mL of a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 9:

1. Then, 1–20 μL of acetone was added to the mixed solvent, and the mixture was stirred at 500–700 rpm for 15–20 h to obtain a lead iodide solution. 90 mg of formamidinium hydroiodate, 6.39 mg of methylammonium iodide, and 9 mg of methylammonium chloride were dissolved in 1 mL of isopropanol, and the mixture was stirred at 500–700 rpm for 15–20 h to obtain an organic mixture solution. b. Preparation of the perovskite active layer Lead iodide solution was spin-coated onto an ammonium iodide-modified double SnO2 electron transport layer, and then annealed at 65–75 °C for 1–3 min to obtain a lead iodide film; then 60–120 μL of organic mixture solution was spin-coated onto the lead iodide film, and then annealed at 140–180 °C for 20–40 min to obtain a perovskite active layer. 4) Preparation of the passivation layer on the surface of phenylethyl ammonium iodide Dissolve 2–4 mg of phenylethyl ammonium iodide in 1 mL of isopropanol and stir at 500–700 rpm for 15–20 h to obtain a phenylethyl ammonium iodide solution; spin-coat the phenylethyl ammonium iodide solution onto the perovskite active layer to prepare a phenylethyl ammonium iodide surface passivation layer. 5) Fabrication of the spiro-OMeTAD hole transport layer Preparation of hole transport layer solution 72.3 mg of spiro-OMeTAD was dissolved in 1 mL of chlorobenzene and stirred at 500–700 rpm for 1–2 h to obtain the original spiro-OMeTAD solution; 520 mg of LiTFSI was dissolved in 1 mL of acetonitrile and stirred at 500–700 rpm for 1–2 h to obtain the LiTFSI acetonitrile solution; 17.6 μL of the LiTFSI acetonitrile solution and 28.5 μL of 4-tert-butylpyridine solution were added to the original spiro-OMeTAD solution and stirred at 500–700 rpm for 10–15 h to obtain the hole transport layer solution; b. Preparation of the hole transport layer The hole transport layer solution was spin-coated onto the passivation layer on the surface of phenylethyl ammonium iodide to prepare the spiro-OMeTAD hole transport layer. 6) Ag electrode preparation At a pressure of 1×10 -4 ~1×10 -3 Under the condition of Pa, Ag electrodes were deposited on the spiro-OMeTAD hole transport layer at a growth rate of [value missing]. Thus, a perovskite solar cell based on an ammonium iodide double electron transport layer and an acetone-doped lead iodide precursor was obtained.

2. The method for fabricating a perovskite solar cell based on an ammonium iodide double electron transport layer and an acetone-doped lead iodide precursor as described in claim 1, characterized in that: In step 2), the spin coating speed is 3000-6000 rpm and the spin coating time is 20-40 s.

3. The method for fabricating a perovskite solar cell based on an ammonium iodide double electron transport layer and an acetone-doped lead iodide precursor as described in claim 1, characterized in that: In step 3), the spin coating speed of the lead iodide solution is 1800-2200 rpm and the spin coating time is 20-30 s; the spin coating speed of the organic mixture solution is 1800-2200 rpm and the spin coating time is 25-35 s.

4. The method for fabricating a perovskite solar cell based on an ammonium iodide double electron transport layer and an acetone-doped lead iodide precursor as described in claim 1, characterized in that: In step 4), the spin coating speed of the phenylethyl ammonium iodide solution is 3000-5000 rpm, and the spin coating time is 30-40 s.

5. The method for fabricating a perovskite solar cell based on an ammonium iodide double electron transport layer and an acetone-doped lead iodide precursor as described in claim 1, characterized in that: In step 5), the spin coating speed of the hole transport layer solution is 3500-4500 rpm, and the spin coating time is 20-30 s.

6. The method for fabricating a perovskite solar cell based on an ammonium iodide double electron transport layer and an acetone-doped lead iodide precursor as described in claim 1, characterized in that: The thickness of the SnO2 electron transport layer is 10–20 nm, the thickness of the ammonium iodide-modified SnO2 electron transport layer is 10–20 nm, the thickness of the perovskite active layer is 0.8–1.2 μm, the thickness of the spiro-OMeTAD hole transport layer is 200–300 nm, and the thickness of the Ag electrode is 80–100 nm.

7. A perovskite solar cell based on an ammonium iodide double electron transport layer and an acetone-doped lead iodide precursor, characterized in that: It is prepared by the method described in any one of claims 1 to 6.

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