High-efficiency perovskite solar cell containing indium-doped SnO2 electron transport layer

Abstract

The invention relates to the technical field of solar cells, in particular to a perovskite solar cell based on indium-doped tin dioxide (SnO2) as an electron transport layer and a preparation method of the perovskite solar cell. The perovskite solar cell has the advantages of high efficiency, low cost, easiness in manufacturing and the like, and becomes a research hotspot in the photovoltaic field in recent years. However, conventional perovskite cells have challenges in terms of long-term stability. According to the invention, the dopant is doped in the SnO2 precursor solution and is used for the electron transport layer, so that the grain surface defect of the SnO2 electron transport layer in the prior art is overcome, the carrier transport is optimized, the growth quality of the perovskite light absorption layer on the electron transport layer is improved, and the photoelectric conversion efficiency is improved. Therefore, the open-circuit voltage, the short-circuit current, the filling factor and the cell conversion efficiency of the perovskite cell device can be improved, and the long-term working stability of the device is enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite solar cells, and particularly relates to a preparation method of an indium-doped tin dioxide electron transport layer and its application in perovskite solar cells. Background Art

[0002] With the rapid development of society and continuous progress of technology, the living standards of humans have been increasing day by day. At the same time, people's demand for energy has also been soaring. Perovskite solar cells are a new type of photovoltaic technology based on perovskite-structured materials and have attracted extensive attention in the photovoltaic field in recent years. The core of this type of battery lies in the use of materials with a perovskite structure. Such materials not only have excellent light absorption ability but also can effectively transport charges, providing new possibilities for improving the performance of solar cells. Compared with traditional silicon-based solar cells, perovskite solar cells have many significant advantages. First of all, their preparation cost is relatively low because perovskite materials can be prepared by solution treatment and other methods, avoiding complex crystal growth and cutting processes. Secondly, perovskite solar cells have a relatively high photoelectric conversion efficiency. Some experimental results show that their efficiency has been comparable to that of commercial silicon-based solar cells. In addition, perovskite solar cells also have characteristics such as being bendable and easy to process, providing a new direction for the innovation of photovoltaic technology. However, the carrier transport efficiency at the upper interface of perovskite solar cells is low due to energy level mismatch, which limits the further development of solar cells. In addition, more defect states at the upper interface of the battery are prone to induce the phase change of perovskite, and the long-term stability of the device in an air environment is poor. In addition, how to improve the efficiency and reduce the cost of perovskite solar cells is also the focus of current research. Among many solutions, modifying the electron transport layer can reduce energy level mismatch and isolate water and oxygen, which is an effective scheme to improve the photoelectric conversion efficiency and stability of the device. Summary of the Invention

[0003] The present invention provides a method for preparing a highly efficient and stable perovskite solar cell containing an indium-doped SnO 2 electron transport layer, using indium chloride to modify the SnO 2 electron transport layer, which solves the problems existing in the prior art.

[0004] A highly efficient perovskite solar cell containing an indium-doped SnO 2 electron transport layer includes, in a stacked order: a conductive layer, an electron transport layer, a perovskite light absorption layer, a hole transport layer, and an electrode; the electron transport layer includes an indium-doped SnO 2 .

[0005] In the indium-doped SnO 2 , the doping amount range of indium is 1-5%.

[0006] A modification material layer is also provided between the perovskite absorption layer and the hole transport layer.

[0007] The indium-doped SnO 2 The preparation method includes the following steps:

[0008] Step 1, prepare a tin salt solution containing a Sn precursor, water, an alcohol solvent, and an acid;

[0009] Step 2, add an indium salt to the tin salt solution, and then add ammonia water for a precipitation reaction;

[0010] Step 3, disperse the obtained precipitate in a solvent to obtain an In-SnO 2 solution;

[0011] Step 4, after heat-treating the SnO 2 solution, indium-doped SnO 2 is obtained.

[0012] In Step 1, the volume ratio of water, the alcohol solvent, and the acid is 5-15:5-15:1, the acid is concentrated hydrochloric acid, and the weight ratio range of the Sn precursor to water is 0.5-1.5:10.

[0013] The Sn precursor is SnCl 2 , the indium salt is indium chloride, and the molar ratio range between the indium salt and the Sn precursor is 0.013-0.065:1.

[0014] The precipitation reaction conditions are first at 40-70°C for 1-5 h, and then at 10-40°C for 10-40 h.

[0015] In Step 3, the solvent is an alcohol solvent; the concentration of the In-SnO 2 solution is 10 μL-10 mg / mL.

[0016] In Step 4, the heat-treatment conditions are at 120-180°C for 10-100 min.

[0017] The preparation method of a perovskite solar cell includes the following steps:

[0018] Spin-coat the In-SnO 2 solution on the conductive layer and perform heat treatment; then sequentially prepare a perovskite light absorption layer and a hole transport layer by a solution method, and then prepare an electrode by evaporation coating.

[0019] The beneficial effects of the present invention are:

[0020] In the present invention, the SnO 2 nanoparticles are prepared by a SnO 2 precursor solvent method, specifically:

[0021] 1) Mix a mixed solution of water and absolute ethanol with SnCl 2 ·2H 2 O, and synthesize high-purity, highly crystalline, small-sized SnO 2 nanoparticles in a low-temperature (<80 °C) environment;

[0022] 2) The SnO 2 nanoparticles doped with indium can be dispersed in solutions such as ethanol.

[0023] 3) The In-SnO 2 nanoparticles dispersed in ethanol proposed by the present invention, when used to prepare the electron transport layer of a battery, can achieve a suitable thickness of the electron transport layer with only one spin coating, meeting the device standards, greatly reducing the workload, and improving the integrity of the electron transport layer and the stability of the device;

[0024] 4) The present invention uses In-SnO 2 to prepare the electron transport layer. Since indium can optimize the surface defects of SnO 2 nanocrystals, the quality of the electron transport layer obtained by spin coating and annealing of SnO 2 is higher;

[0025] 5) In the In-SnO 2 electron transport layer prepared by the present invention, the crystallization growth of the perovskite light-absorbing layer on the surface of the electron transport layer is improved, reducing the perovskite buried bottom interface and bulk phase defects, and thus improving the open-circuit voltage and photoelectric conversion efficiency of the device;

[0026] 6) The preparation process of the present invention is simple, the production conditions are mild, the cost is low, and the repeatability is high, which is helpful for the commercial application of perovskite solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a physical picture of the prepared In-SnO 2 nanoparticle powder.

[0028] Figure 2 is the X-ray diffraction pattern (XRD) of SnO 2 prepared in Preparation Example 1.

[0029] Figure 3 is the scanning electron microscope image (SEM) of the prepared 30 nm In-SnO 2 nanoparticles.

[0030] Figure 4 is a schematic diagram of the device structure of a perovskite solar cell containing an indium-doped SnO 2 electron transport layer.

[0031] Figure 5For the prepared In-SnO 2 Transmission spectrum of the nanoparticles.

[0032] Figure 6 Current-voltage curves of In-SnO2 perovskite solar cells based on different In doping amounts. Specific implementation mode

[0033] The technical solution of the present invention is described in detail as follows:

[0034] Containing indium-doped SnO 2 A preparation method of an efficient perovskite solar cell with an electron transport layer includes the following steps:

[0035] (1) Dissolve the precursor of Sn in deionized water, and then mix it with ethanol and concentrated hydrochloric acid to obtain a tin salt solution;

[0036] (2) Add indium chloride (InCl 3 ) to the tin salt solution under stirring, then drop a few drops of concentrated ammonia water, and then perform magnetic stirring at a temperature of 60 °C. After 2 hours, a precursor solution is obtained;

[0037] (3) Filter the precursor solution after standing for 24 hours, take the precipitate, wash, centrifuge, and dry it to obtain indium-doped SnO 2 powder. Disperse the indium-doped SnO 2 powder in a solvent to obtain indium-doped SnO 2 solution;

[0038] (4) Coat the indium-doped SnO 2 solution on a substrate, and then anneal it at 150 °C for 30 min to obtain an indium-doped SnO 2 electron transport layer.

[0039] In step (1), the precursor of SnO 2 is tin dichloride dihydrate (SnCl 2 ·2H 2 O).

[0040] The preparation process of the SnO 2 nanoparticles is specifically as follows: Dissolve the precursor of SnO 2 in a mixed solution of water and absolute ethanol, heat, stir, age, filter, and centrifuge to obtain a solid; After purification and separation, SnO 2 nanoparticles are obtained.

[0041] The volume ratio of the water to the absolute ethanol is 1:1.

[0042] The heating temperature is 60 °C, the stirring time is 2 hours, and the aging time is 24 hours.

[0043] The specific implementation of the centrifugation treatment is to first wash the solid 3 - 5 times with a mixed solution of ethanol and water, and then centrifuge at a speed of 6000 rpm for 15 minutes.

[0044] The dispersion liquid is obtained by ultrasonically dispersing SnO 2 nanoparticles in an alcohol solvent.

[0045] The prepared indium-doped SnO 2 Application in an efficient perovskite solar cell with an electron transport layer, and the perovskite solar cell is a p-type perovskite solar cell.

[0046] An efficient perovskite solar cell containing an indium-doped SnO 2 electron transport layer, and the perovskite solar cell with the indium-doped SnO 2 electron transport layer is a p-type perovskite solar cell; the p-type perovskite solar cell includes a transparent conductive substrate, an electron transport layer, a perovskite layer, a hole transport layer, and a metal electrode layer from bottom to top in sequence;

[0047] The electron transport layer is prepared by using the described preparation method.

[0048] A preparation method for an efficient perovskite solar cell containing an indium-doped SnO 2 electron transport layer, and the perovskite solar cell with the indium-doped SnO 2 electron transport layer is a p-type perovskite solar cell. The preparation process is as follows: on a transparent conductive substrate, a dispersion liquid of indium-doped SnO 2 nanoparticles is coated to obtain an electron transport layer containing indium-doped SnO 2 , and the electron transport layer containing indium-doped SnO 2 is prepared by using the described preparation method; then the perovskite layer, the hole transport layer, and the metal electrode layer are prepared in sequence;

[0049] A preparation method for an efficient perovskite solar cell containing an indium-doped SnO 2 electron transport layer, and the device structure of the perovskite solar cell with the indium-doped SnO 2 electron transport layer is: FTO / In-SnO 2 / FA 0.9 Cs 0.1 PbI 3 / Spiro-OMeTAD / Ag.

[0050] The described one containing indium-doped SnO2 Preparation method of efficient perovskite solar cell with electron transport layer, comprising the following steps:

[0051] 1) FTO pretreatment: First, the FTO substrate is ultrasonically treated with deionized water, ethanol, and acetone for 30 minutes in sequence, and the cleaned FTO is dried with nitrogen and stored for later use;

[0052] 2) Indium-doped SnO 2 Preparation of electron transport layer: By spin coating, the indium-doped SnO 2 solution is coated at a rotation speed of 4000 for 30 seconds, and then annealed at 150 °C for 30 minutes; Subsequently, the perovskite thin film is spin-coated and deposited in a glove box filled with nitrogen, and transferred to an environment with a relative humidity of 30% - 40% for annealing treatment for 15 minutes; Then, the Spiro-OMeTAD hole transport layer is spin-coated;

[0053] 3) Preparation of back electrode: A layer of Ag is grown as the back electrode by thermal evaporation, that is, a perovskite solar cell including an indium-doped SnO 2 electron transport layer is obtained.

[0054] Example 1 Preparation of SnO 2 solution

[0055] Dissolve 0.9 g of SnCl 2 ·2H 2 O in 10 ml of deionized water, then mix it with 10 ml of ethanol and 1 ml of concentrated hydrochloric acid to obtain a tin salt solution; The temperature is 60 °C, and a precursor solution is obtained after 2 hours;

[0056] After the precursor solution is left standing for 24 hours, it is filtered, and the precipitate is washed 3 - 5 times with ethanol and water, and then centrifuged at a rotation speed of 6000 rpm for 15 minutes. After drying at 60 °C for 24 hours, SnO 2 powder is obtained, and the particle size of the SnO 2 nanoparticles is 30 - 40 nm. The powder is dispersed in ethanol to obtain a SnO 2 ethanol solution.

[0057] Example 2 Preparation of indium-doped SnO 2 solution

[0058] Dissolve 0.9 g of SnCl 2 ·2H 2 O (converted to 0.6 g of SnO 2 ) in 10 ml of deionized water, then mix it with 10 ml of ethanol and 1 ml of concentrated hydrochloric acid to obtain a tin salt solution;

[0059] 0.0345 g of InCl was added to the tin salt solution under stirring. 3 Then, a few drops of concentrated ammonia water were added dropwise, followed by magnetic stirring at a temperature of 60 °C. After 2 hours, a precursor solution was obtained.

[0060] The precursor solution was filtered after standing for 24 hours. The precipitate was washed 3 - 5 times with ethanol and water, and then centrifuged at 6000 rpm for 15 min. After drying at 60 °C for 24 hours, indium-doped SnO 2 powder was obtained. The indium doping amount was 3% calculated according to In / SnO 2 . The particle size of the nanoparticles was 30 - 40 nm. The powder was dispersed in ethanol to obtain an ethanol solution of In-SnO 2 .

[0061] In the same way, nanoparticles with indium doping amounts of 1% and 5% were prepared for parallel experiments.

[0062] Application Example 1

[0063] This embodiment provides a preparation process for a normal perovskite solar cell (FTO transparent conductive substrate / electron transport layer In-SnO 2 / perovskite layer PVK / hole transport layer Spiro-OMeTAD / metal electrode layer Ag), and its steps mainly include:

[0064] 1) Cleaning of the FTO transparent conductive substrate: The FTO conductive glass substrate was ultrasonically cleaned successively with an FTO cleaning agent, water, a mixed solution of ethanol and acetone (Vethanol:Vacetone = 1:1), and water, and then dried with a nitrogen gun and treated with ozone for 10 min.

[0065] 2) Preparation of the indium-doped SnO 2 electron transport layer: 10 μL of the 10 mg / mL SnO 2 nanoparticle dispersion prepared in Preparation Example 1 was spin-coated on the FTO transparent conductive substrate at a spin-coating speed of 3000 rpm for 40 s, and pre-annealed at 150 °C for 30 min to obtain the electron transport layer.

[0066] 3) Preparation of the perovskite layer: 760.65 mg of lead iodide (PbI 2 ), 246.9 mg of formamidinium hydroiodide (FAI), 18.72 mg of cesium iodide (CsI), and 21.95 mg of methylammonium chloride (MACl) were mixed and dissolved in 1 mL of a mixed solution of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) and stirred for 3 hours to prepare a perovskite precursor solution. Then, the perovskite precursor solution was spin-coated on the indium-doped SnO 2On the electron transport layer, first spin-coat at 1500 rpm for 10 s, then spin-coat at 3000 rpm for 40 s. After spin-coating, anneal to obtain the perovskite light absorption layer. The annealing temperature is 120 °C and the time is 15 min.

[0067] 4) Preparation of the hole transport layer: Add 90 mg of Spiro-OMeTAD, 28.5 μL of tributyl phosphate (TBP), 17.8 μL of lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) and a mixed solution of acetonitrile (ACN) (520 mg / mL Li-TFSI dissolved in ACN), 20 μL of a mixed solution of FK209 and acetonitrile (ACN) (200 mg / mL FK209 dissolved in ACN) into 1 mL of chlorobenzene (CB) and stir for 5 hours to prepare a Spiro-OMeTAD precursor solution. Then spin-coat 28 μL of the prepared Spiro-OMeTAD precursor solution at a spin-coating speed of 4000 rpm for 40 s without annealing treatment to obtain the hole transport layer;

[0068] 5) Preparation of the metal electrode layer: Deposit the Ag metal electrode by thermal evaporation. The evaporation current is 40 A and the rate is 0.05 nm / s until it reaches 100 nm.

[0069] Comparative Example 1

[0070] A perovskite solar cell containing SnO 2 in the electron transport layer, which is different from Application Example 1 in that: in this embodiment, the preparation of the electron transport layer uses a halogen-free modified SnO 2 solution, and other materials, structures and preparation methods are the same as those in Example 1.

[0071] The physical picture of the indium-doped SnO2 powder prepared in Example 1 is as Figure 1 shown, and the product is a white powder. The XRD pattern of the SnO 2 prepared in Comparative Example 1 is as Figure 2 shown, which corresponds one by one to the XRD standard card of SnO 2 . The SEM picture of the indium-doped SnO 2 prepared in Example 1 is as Figure 3 shown, with a size of about 30 nm.

[0072] According to the SnO 2 and In-SnO 2 prepared in Example 1 and Comparative Example 1, through the formula to calculate the electron mobility, the calculation results show that indium doping can significantly improve the electron mobility of SnO 2 to reach 7.0965 cm 2 ·V -1·s -1 Compared with SnO 2 , the electron mobility (0.5868 cm 2 ·V -1 ·s -1 ) is increased by about 12 times. According to the In-SnO 2 prepared in Example 1 and Comparative Example 1, its optical transmittance was analyzed using UV-Vis. The measurable wavelength range of the transmittance is between 300 nm and 800 nm. It is found that the transmittance of the In-SnO 2 thin film is higher than 90% in the visible light range, and the results are as shown in Figure 5 . The perovskite solar cell structure with an indium-doped SnO 2 electron transport layer prepared according to Example 1 is as shown in Figure 5 . The transparent conductive substrate is FTO, the electron transport layer is In-SnO 2 , the hole transport layer is Spiro-OMeTAD, and the metal electrode is Ag.

[0073] The photoelectric conversion efficiency of the perovskite solar cell devices in Example 1 and Comparative Example 1 was tested, and the performance of In-SnO 2 with different In dopings was compared. The current density-voltage curve graphs of the perovskite solar cell devices in Example 1 and Comparative Example 1 were obtained through sunlight simulation tests, and the results are as shown in Figure 6 and Table 1. The results show that the device prepared according to the modification material described in Example 1 improves the photoelectric conversion efficiency of the battery, and the optimal doping amount is 3%.

[0074] Table 1. Performance of perovskite solar cells with SnO 2 electron transport layer based on different In doping amounts

[0075]

Claims

1. A high-efficiency perovskite solar cell containing an indium-doped SnO2 electron transport layer, characterized in that: It includes the following stacked layers: a conductive layer, an electron transport layer, a perovskite light absorption layer, a hole transport layer, and an electrode; the electron transport layer includes indium-doped SnO2.

2. The high-efficiency perovskite solar cell containing an indium-doped SnO2 electron transport layer according to claim 1, characterized in that: In the indium-doped SnO2, the doping amount of indium is in the range of 1-5%. A modification material layer is also provided between the perovskite absorption layer and the hole transport layer.

3. The high-efficiency perovskite solar cell containing an indium-doped SnO2 electron transport layer according to claim 1, characterized in that: The preparation method of indium-doped SnO2 comprises the following steps: step 1, preparing a tin salt solution containing a Sn precursor, water, an alcohol solvent and an acid; step 2, adding an indium salt to the tin salt solution, and then adding ammonia water to carry out a precipitation reaction; step 3, dispersing the obtained precipitate in a solvent as an In-SnO2 solution; step 4, heat-treating the SnO2 solution to obtain indium-doped SnO2.

4. The high-efficiency perovskite solar cell containing an indium-doped SnO2 electron transport layer according to claim 1, characterized in that: In step 1, the volume ratio of water, alcohol solvent and acid is 5-15:5-15:1, the acid is concentrated hydrochloric acid, and the weight ratio of Sn precursor to water is in the range of 0.5-1.5:

10.

5. The high-efficiency perovskite solar cell containing an indium-doped SnO2 electron transport layer according to claim 1, characterized in that: The precursor of Sn is SnCl2, the indium salt is indium chloride, and the molar ratio between the indium salt and the precursor of Sn is in the range of 0.013-0.065:

1.

6. The high-efficiency perovskite solar cell containing an indium-doped SnO2 electron transport layer according to claim 1, characterized in that: The precipitation reaction conditions are first at 40-70°C for 1-5h, and then at 10-40°C for 10-40h.

7. The high-efficiency perovskite solar cell containing an indium-doped SnO2 electron transport layer according to claim 1, characterized in that: In step 3, the solvent is an alcohol solvent; the concentration of the In-SnO2 solution is 10 μL-10 mg / mL.

8. The high-efficiency perovskite solar cell containing an indium-doped SnO2 electron transport layer according to claim 1, characterized in that: In step 4, the heat treatment condition is 120-180° C. for 10-100 min.

9. The method for preparing a perovskite solar cell according to claim 1, characterized in that: The method comprises the following steps: spin coating an In-SnO2 solution on a conductive layer and performing heat treatment; then sequentially preparing a perovskite light absorption layer and a hole transport layer by a solution method, and then preparing an electrode by an evaporation method.

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