Catalytic assisted iodine reduction perovskite thin film and trans-perovskite solar cell

Abstract

The invention provides a trans-perovskite thin film for catalyzing and assisting iodine reduction and a perovskite solar cell. The perovskite solar cell comprises a bottom electrode, a hole transport layer, a perovskite thin film layer, an electron transport layer and a top electrode. The catalytic assisted iodine reduction is characterized in that the pyridylated carbon nanotubes are dispersed and then doped into a perovskite solution so as to assist in reduction of iodine elementary substances in perovskite. The pyridinized carbon nanotubes can catalyze reduction of iodine elementary substances through surface nitrogen active sites, perovskite degradation caused by escape of the iodine elementary substances is avoided, and thus a perovskite device with higher stability is prepared. According to the invention, the pyridinized carbon nanotubes are introduced into the perovskite precursor to catalyze and assist the reduction of iodine, so that the performance degradation of the device caused by iodine escape in the use process of the perovskite device is avoided, and the method has a wide application prospect in the field of perovskite solar cells.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a perovskite thin film with catalytic auxiliary iodine reduction and a trans perovskite solar cell. BACKGROUND

[0002] Perovskite solar cells have become the representative of the third generation of solar cells because of their excellent photoelectric conversion efficiency and low material cost. Halide perovskite solar cells dominated by iodine have become the current mainstream research object because of their high theoretical efficiency. Iodide perovskite devices will decompose to produce elemental iodine during long-term use, which not only accelerates its own decomposition and aging, but also corrodes the electrode, causing irreversible loss of device performance. At present, in order to inhibit iodine escape, various schemes have been developed, including the initial improvement of iodine migration mainly by optimizing crystallization and defect passivation, and then various iodine capture technologies are designed to achieve iodine binding, so that iodine and lead spontaneously react. On this basis, researchers have developed various redox strategies to accelerate the reduction of iodine. However, the redox strategy may cause other materials in the perovskite to react, leading to decomposition of the perovskite. Therefore, it is crucial to accelerate the reduction of iodine while avoiding other reactions to improve the stability of the device. SUMMARY

[0003] Therefore, the purpose of the present application is to provide a trans perovskite thin film with catalytic auxiliary iodine reduction and a perovskite solar cell to solve the problem of iodine escape caused by photothermal aging during the use of perovskite solar cells. Pyridyl carbon nanotubes can assist the reaction between iodine and Pb through catalysis based on the adsorption of elemental iodine, achieving the effect of inhibiting iodine escape. At the same time, the pyridyl group improves the quality of the thin film, and a perovskite device with high crystallinity is prepared, achieving excellent stability while having high photovoltaic conversion efficiency.

[0004] The specific technical scheme to achieve the purpose of the present application is as follows:

[0005] A preparation method of a perovskite thin film with catalytic auxiliary iodine reduction, the perovskite thin film material is various perovskite materials ABX3, wherein A is one or more of cesium ions, methylamine ions and formamidinium ions, B is one or more of lead ions, tin ions and germanium ions, and X is one or more of halide anions containing I and thiocyanate ions; the preparation includes the following steps:

[0006] Step 1, preparation of precursors:

[0007] AX and BX2 are dissolved in anhydrous solvent N, N-dimethylformamide (DMF) and DMSO in a molar ratio of 1:1-1.15, the volume ratio of DMF and DMSO is 4:1, and the solute is completely dissolved by stirring to obtain a perovskite precursor solution, then 0.01-0.2 mg / mL pyridyl carbon nanotubes are added for dispersion; wherein A is one or more of cesium ions, methylamine ions, formamidine ions, B is one or more of lead ions, tin ions, germanium ions, and X is one or more halide anions containing I;

[0008] The pyridyl carbon nanotubes are dissolved in a mixed solution of anhydrous N, N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1 at a concentration of 0.05-0.5 g / mL, and the mixture is stirred to obtain an additive solution;

[0009] Step 2, the prepared additive solution is added to the perovskite precursor solution to obtain an optimized perovskite precursor solution, and the concentration of the added additive solution is 0.5 mg / mL or less but not 0 mg / mL;

[0010] Step 3, the optimized perovskite precursor solution is spin-coated on the substrate layer by a spin coater, and a stability-optimized perovskite thin film is prepared after annealing; the process of spin-coating on the substrate layer is divided into two stages, specifically:

[0011] The first stage is at a speed of 1000-2000 rpm for 10 s, and the second stage is at a speed of 3000-5000 rpm for 30-50 s, then 20-40 μL / cm 2 A reverse solvent, i.e. chlorobenzene or anisole, is added, and then the mixture is treated on a heating table at 100-130 ℃ for 15-20 min to form a perovskite thin film layer.

[0012] A perovskite thin film prepared based on the above method.

[0013] A trans perovskite solar cell, which has a structure from bottom to top as follows: a bottom electrode, a hole transport layer, a perovskite thin film layer, an electron transport layer, and a metal electrode layer, wherein the perovskite thin film layer is the perovskite thin film prepared according to the above method.

[0014] A preparation method of the trans perovskite solar cell, comprising the following specific steps:

[0015] Providing a glass substrate etched with ITO or FTO;

[0016] Forming a hole transport layer on the substrate;

[0017] and forming the perovskite thin film layer on the hole transport layer;

[0018] and forming an electron transport layer on the perovskite thin film;

[0019] and forming a metal electrode layer on the electron transport layer.

[0020] The perovskite device prepared by the method has improved stability and photovoltaic performance. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Figure 1 is a structural schematic diagram of the perovskite solar cell of the present application;

[0022] Figure 2 Figure 5 is a cyclic voltammogram of the catalytic performance effect of the pyridyl carbon nanotube;

[0023] Figure 3 Figure 7 is an XPS graph of the thin film with or without the addition of the pyridyl carbon nanotube;

[0024] Figure 4 Figure 9 is a surface morphology picture before and after the addition of the pyridyl carbon nanotube;

[0025] Figure 5 Figure 11 is a stability curve of the 1.52eV band gap perovskite solar cell with or without the pyridyl carbon nanotube;

[0026] Figure 6 Figure 13 is a photovoltaic performance curve of the 1.52eV band gap perovskite solar cell with or without the pyridyl carbon nanotube. DETAILED DESCRIPTION

[0027] The content of the present application will be further described in detail below in combination with the drawings and examples, in order to make the skilled in the art more clearly understand the technical solutions described in the present application, the following examples are listed for illustration. It should be pointed out that the following examples do not constitute a limitation on the scope of protection required by the present application.

[0028] The present application provides an additive for catalytic auxiliary iodine reduction, the concentration of the additive pyridyl carbon nanotube in the perovskite precursor is 0.01-0.2 mg / mL. When applied in perovskite solar cells, considering that too low content of pyridyl carbon nanotube will weaken the binding ability of iodine, and too high concentration will affect the performance of the device, the preferred concentration of the additive is 0.05-0.5 mg / mL.

[0029] The perovskite ABX3 material is one or more of cesium ion, methylamine ion, formamidine ion, one or more of lead ion, tin ion, germanium ion, and one or more of halide anion containing I and thiocyanate ion.

[0030] The structure of the perovskite solar cell includes, from bottom to top, a conductive substrate, a hole transport layer, a perovskite thin film layer, an electron transport layer, and a metal electrode.

[0031] The conductive substrate is one of ITO or FTO, and the purchased ITO or FTO glass is sequentially subjected to ultrasonic treatment with deionized water, acetone, and isopropanol to clean the glass surface, and then dried with nitrogen, and then placed in ultraviolet ozone for 10-30 min.

[0032] The hole transport layer is one or more of [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl] phosphonic acid (MeO-2PACz), [4-(7H-dibenzo[c,g]carbazol-7-yl)butyl] phosphonic acid (4PADCB), and poly[3-(methylammonium butanoate) thiophene] (P3CT-N); the process parameters of the hole transport layer are: rotation speed 3000-5000 rpm, time 20-30 s; the annealing process parameters are: annealing temperature 80-120 ℃, time 5-10 min.

[0033] The perovskite thin film contains pyridine carbon nanotubes, Preparation The process parameters of the perovskite thin film layer are: rotation speed 3000-5000 rpm, spin coating for 30-50 s, and then adding 20-40 μL / cm at the 10th-15th second. 2 Anti-solvent (chlorobenzene or anisole), followed by heating on a heating table at 100-130 ℃ for 15-20 min to form a perovskite thin film layer.

[0034] The electron transport layer includes C 60 layer and TPBi layer, and TPBi is a hole blocking layer. The C 60 layer has a thickness of 30-45 nm, and the TPBi layer has a thickness of 6-10 nm. 60 Both the C

[0035] The thickness of the metal electrode is 80-200 nm, and the material is not limited, but considering the conductivity and work function of the metal, the electrode is preferably an Ag electrode, and the thickness is preferably 100 nm.

[0036] In the following, the perovskite thin film and the preparation method of the perovskite solar cell will be further described through specific examples.

[0037] Example

[0038] like Figure 1 As shown, the perovskite solar cell comprises an ITO glass substrate 1, a hole transport layer 2, a perovskite thin film layer 3, an electron transport layer 4, and a metal electrode 5, which are sequentially stacked. The fabrication method is as follows:

[0039] Using a 2cm×2cm ITO-etched glass as substrate 1, the glass surface was cleaned by ultrasonication with deionized water, acetone, and isopropanol in sequence. After being dried with nitrogen, it was placed in ultraviolet ozone for 20 minutes before use.

[0040] Hole transport layer 2 was deposited on the treated ITO glass substrate using a solution spin-coating method. Transport layer 2 was a MeO-2PACz material layer, formed by spin-coating a MeO-2PACz ethanol solution with a concentration of 0.5 mg / mL, a spin coater speed of 4000 rpm, a spin-coating time of 30 s, and annealing at 100 ℃ for 10 min.

[0041] The perovskite thin film layer 3 is spin-coated onto the hole transport layer 2, specifically by the following method:

[0042] Perovskite solution: 10.8 mg MACl, 20.7 mg CsI, 25.3 mg MAI, 238.1 mg FAI, and 791.6 mg PbI2 were dissolved in 1 mL of a mixed solvent of DMF and DMSO at a volume ratio of 4:1, followed by stirring to dissolve. Perovskite films were prepared by spin coating in a glove box. The spin coating program was 1000 rpm (10 s) + 5000 rpm (40 s). At the remaining 10 s, 150 μL of chlorobenzene was added, followed by annealing on a 100 ℃ heating stage for 30 min to complete the perovskite film crystallization process.

[0043] The perovskite film was then post-treated by depositing 0.5 mg / mL of 1,3-diaminopropane dihydroiodate (PDAI2) onto the perovskite film via spin coating at a speed of 4000 rpm (30 s) and annealing at 100 °C for 5 min.

[0044] An electron transport layer 4 is fabricated on the perovskite thin film layer 3, specifically as follows:

[0045] A C layer with a thickness of 30 nm was sequentially deposited using a vacuum thermal evaporation method. 60 The layer consists of a 6 nm TPBi layer.

[0046] A layer of silver with a thickness of 100 nm was deposited on electron transport layer 4 using vacuum evaporation as electrode 5.

[0047] Referring to Figure 2 , the cyclic voltammogram of the pyridine carbon nanotube catalytic performance of the invention. It can be seen that the iodine reduction potential of the carbon nanotube without pyridine is 0.145 V, and the iodine reduction potential of the carbon nanotube with pyridine as the electrode is 0.151 V. The movement of the reduction potential to the positive potential indicates that the difficulty of iodine reduction is reduced, indicating that the pyridine carbon nanotube catalyzing auxiliary iodine reduction function.

[0048] Referring to Figure 3 , the XPS graph of the thin film before and after aging with or without pyridine carbon nanotubes. It can be seen that the thin film without adding pyridine carbon nanotubes and adding carbon nanotubes appears Pb0 signal peak after aging, while the spectrum of adding pyridine carbon nanotubes does not appear, indicating that pyridine carbon nanotubes effectively catalyze the reduction of iodine.

[0049] Referring to Figure 4 , the surface morphology picture before and after adding pyridine carbon nanotubes. It can be seen that the grain size of the thin film without adding pyridine carbon nanotubes is small and uneven, and there are holes on the surface, while the grain size of the thin film with pyridine carbon nanotubes is obviously increased, and the uniformity is improved, indicating that pyridine carbon nanotubes can effectively improve the crystallization and obtain perovskite thin film with higher crystallinity.

[0050] Referring to Figure 5 , the stability curve of 1.52 eV band gap perovskite solar cell with or without pyridine carbon nanotubes. The prepared perovskite solar cell was tested for long time 85 ℃ aging, and the device stability of the device with pyridine carbon nanotubes was significantly better than that of the blank device and the device with carbon nanotubes, and the efficiency retention rate after 1000 h aging reached 96.9%.

[0051] Referring to Figure 6 , the performance curve of 1.52 eV band gap perovskite solar cell with or without pyridine carbon nanotubes. The prepared perovskite solar cell was tested for performance, and the device performance of the device with pyridine carbon nanotubes was significantly better than that of the blank device, and the open circuit voltage and fill factor were increased to 1.19 V and 84.16%, respectively, and the efficiency reached 26.59%.

Claims

1. A method for preparing a perovskite thin film with catalytic-assisted iodine reduction, characterized in that, The perovskite thin film material is a perovskite material ABX3, wherein A is one or more of cesium ions, methylamine ions and formamidinium ions, B is one or more of lead ions, tin ions and germanium ions, and X is one or more of halide anions and thiocyanate ions that must contain I. Its preparation includes the following steps: Step 1, Preparation of precursors: AX and BX2 were dissolved in anhydrous N,N-dimethylformamide (DMF) and DMSO at a molar ratio of 1:1-1.15, with a volume ratio of DMF to DMSO of 4:

1. The mixture was stirred until the solutes were completely dissolved to obtain a perovskite precursor solution. Then, 0.01-0.2 mg / mL of pyrided carbon nanotubes were added for dispersion. In this solution, A is one or more of cesium ions, methylamine ions, and formamidinium ions; B is one or more of lead ions, tin ions, and germanium ions; and X is one or more halide anions containing I. Pyrided carbon nanotubes were dissolved at a concentration of 0.05-0.5 g / mL in a mixed solution of anhydrous N,N-dimethylformamide and dimethyl sulfoxide at a volume ratio of 4:1, and the mixture was stirred to obtain an additive solution. Step 2: Add the prepared additive solution to the perovskite precursor solution to obtain the optimized perovskite precursor solution. The concentration of the added additive solution is less than 0.5 mg / mL but not 0 mg / mL. Step 3: The optimized perovskite precursor solution is spin-coated onto the substrate using a spin coater, followed by annealing to obtain a perovskite film with optimized stability. The spin-coating process onto the substrate consists of two stages, specifically: The first stage involves a rotation speed of 1000-2000 rpm for 10 seconds; the second stage involves a rotation speed of 3000-5000 rpm for 30-50 seconds; and then, in the last 10-15 seconds, 20-40 μL / cm³ is added. 2 The antisolvent is chlorobenzene or anisole, and then the mixture is treated on a heating stage at 100-130 °C for 15-20 minutes to form a perovskite thin film layer.

2. A perovskite thin film prepared by the method of claim 1.

3. A reverse perovskite solar cell, characterized in that, The inverted perovskite solar cell structure, from bottom to top, consists of: a bottom electrode, a hole transport layer, a perovskite thin film layer, an electron transport layer, and a metal electrode layer, wherein the perovskite thin film layer is the perovskite thin film as described in claim 2.

4. A method for preparing an inverted perovskite solar cell according to claim 3, characterized in that, The specific steps include the following: Provide a glass substrate for etching ITO or FTO; A hole transport layer is formed on the substrate; And the perovskite thin film layer is formed on the hole transport layer; And an electron transport layer is formed on the perovskite thin film; And a metal electrode layer is formed on the electron transport layer.

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