Method for preparing TiO2 electron transport layer for perovskite solar cell at low temperature

Abstract

The invention relates to a preparation method of a TiO2 electron transport layer for a perovskite solar cell, belongs to the technical field of perovskite solar cell preparation, and solves the problem that the improvement of the performance of the perovskite solar cell is limited because crystal grain agglomeration is easy to occur in the prior art, and the preparation method comprises the following steps: cleaning FTO (Fluorine-doped Tin Oxide) conductive glass; placing the clean FTO conductive glass substrate under an ultraviolet lamp of ultraviolet ozone surface treatment equipment for irradiation treatment; preparing a titanium dioxide precursor solution; flatly laying the FTO conductive glass substrate cleaned by the ultraviolet ozone in a culture dish, and then slowly pouring the titanium dioxide water bath precursor solution into the culture dish until the FTO conductive glass substrate is immersed in the culture dish; the culture dish containing the FTO conductive glass substrate is placed in a drying oven for reaction, and a uniform TiO2 electron transport layer is obtained on the FTO conductive glass substrate; and taking out the FTO conductive glass substrate with the TiO2 electron transport layer, washing the FTO conductive glass substrate with deionized water and ethanol in sequence, and blow-drying the FTO conductive glass substrate with nitrogen to obtain the final TiO2 electron transport layer.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite solar cell preparation, and in particular to a method for preparing a perovskite solar cell at low temperature using TiO 2 Electron transport layer method. Background Art

[0002] Metal halide perovskite solar cells have the advantages of high photoelectric conversion efficiency, solution preparation, and low cost, and have attracted widespread attention in recent years. The structure of perovskite solar cells mainly includes: transparent conductive substrate, electron transport layer, perovskite light absorption layer, hole transport layer and counter electrode. Compared with mesoporous perovskite solar cells, planar perovskite solar cells have outstanding application potential in the field of flexible devices and stacked devices. In planar perovskite solar cells, the most commonly used inorganic electron transport layer material is TiO 2 SnO 2 and ZnO.

[0003] TiO 2 As an n-type semiconductor often used as an electron transport layer material, it has many advantages, such as: energy level structure matching that of perovskite, large energy band gap, wide range of light transmittance in the ultraviolet and visible light regions, and low preparation cost. 2 The preparation method of the electron transport layer and its structural morphology have a great influence on the performance of solar cell devices. At present, the commonly used preparation methods of the electron transport layer include thermal evaporation, electron beam evaporation, atomic layer deposition, magnetron sputtering, spin coating, chemical water bath method, etc. Among them, the chemical water bath method has the advantages of simple process, low preparation temperature, and film formation, which is very compatible with the preparation process of perovskite solar cells.

[0004] However, the current mainstream chemical water bath method is through TiCl 4 Hydrolysis to prepare TiO 2 The electron transport layer, however, includes a violent hydrolysis process and a nucleation crystallization process, which is prone to grain agglomeration and the generation of oxygen vacancy defects, which in turn leads to low electron mobility of titanium dioxide and affects the interface contact with the perovskite film, limiting the performance improvement of perovskite solar cells. In addition, the low pH value caused by the strong acid (HCl) in the chemical bath limits the application of this chemical water bath method on acid-sensitive substrates (such as flexible transparent conductive oxides (TCO) and ITO).

[0005] Therefore, the technical field requires a method for preparing an electron transport layer that can limit grain agglomeration to improve the performance of perovskite solar cells and overcome the effects of strong acid in a chemical bath. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a low-temperature preparation method of TiO2 for perovskite solar cells. 2 The method of the electron transport layer aims to prepare titanium dioxide by regulating the deposition process of titanium dioxide in a chemical water bath, moderate the hydrolysis rate, and regulate the nucleation and growth of titanium dioxide grains to solve the problems of titanium dioxide grain agglomeration and poor interface contact performance with perovskite film, thereby improving the photoelectric conversion efficiency of perovskite solar cells.

[0007] According to an embodiment of the present invention, a low-temperature preparation method of TiO2 for perovskite solar cells is provided. 2 The method of an electron transport layer comprises the following steps:

[0008] Step S1: cleaning the FTO conductive glass to obtain a clean FTO conductive glass substrate;

[0009] Step S2: placing the clean FTO conductive glass substrate under the ultraviolet lamp of the ultraviolet ozone surface treatment equipment for irradiation treatment to form a hydrophilic surface, thereby obtaining the FTO conductive glass substrate after ultraviolet ozone cleaning;

[0010] Step S3: preparing a titanium dioxide precursor solution, adding titanium sulfate into clean deionized water to obtain a titanium dioxide water bath precursor solution;

[0011] Step S4: Lay the FTO conductive glass substrate after UV ozone cleaning flat in a culture dish, and then slowly pour the titanium dioxide water bath precursor solution into the culture dish until the FTO conductive glass substrate is immersed therein;

[0012] Step S5: Place the culture dish containing the FTO conductive glass substrate in an oven for reaction to obtain a uniform TiO 2 Electron transport layer;

[0013] Step S6: Take the culture dish out of the oven and place the TiO 2 The FTO conductive glass substrate of the electron transport layer was taken out from the culture dish, rinsed with deionized water and ethanol in sequence, and then blown and dried with nitrogen to obtain the final TiO 2 Electron transport layer.

[0014] Optionally, the step S1 specifically comprises: ultrasonically cleaning the FTO conductive glass with deionized water, isopropanol and ethanol in sequence, and drying with nitrogen after cleaning to obtain a clean FTO conductive glass substrate.

[0015] Optionally, the concentration of the titanium dioxide water bath precursor solution prepared in step S3 is 0.04 mol / L to 0.2 mol / L.

[0016] Optionally, in the reaction of step S5, the temperature in the oven is set to 30° C. to 100° C., and the reaction time is set to 30 minc to 90 min.

[0017] Compared with the prior art, a method for preparing TiO2 for perovskite solar cells at low temperature according to an embodiment of the present invention is provided. 2 The electron transport layer approach has at least the following advantages:

[0018] (1) The titanium sulfate used is cheaper than the titanium tetrachloride used in the prior art, and the preparation process is safer. In addition, the high pH value during the hydrolysis of titanium sulfate protects the acid-sensitive substrate from acid corrosion.

[0019] (2) After the titanium dioxide film prepared by the method of the present invention is formed, the smooth surface morphology can improve the interface contact between the titanium dioxide film and the perovskite film;

[0020] (3) The sulfate groups on the surface of the prepared titanium dioxide can combine with the lead atoms of the bottom perovskite film to form an interfacial cross-linking structure, enhance interfacial charge transfer, and improve battery efficiency;

[0021] (4) The operation process is simple, the materials are fully utilized, and it is easy to mass-produce. It has greater potential in the preparation of perovskite solar cells and has higher photoelectric conversion efficiency and good stability.

[0022] (5) In order to improve the efficiency of perovskite solar cells based on titanium dioxide electron transport layers, it is a feasible method to regulate the deposition process of titanium dioxide to achieve controllable growth and uniform coverage of high-quality TiO2 films, and to protect the indium tin oxide (ITO) substrate from acid corrosion, thereby promoting the fabrication of high-performance perovskite solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. The features and advantages of the present invention can be more clearly understood by referring to the drawings. The drawings are schematic and should not be understood as limiting the present invention in any way. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A method for preparing TiO2 for perovskite solar cells at low temperature according to an embodiment of the present invention 2 Process flow diagram of the method for an electron transport layer. DETAILED DESCRIPTION

[0025] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0027] The following is a low-temperature preparation method of TiO2 for perovskite solar cells according to an embodiment of the present invention with reference to the accompanying drawings. 2 The method of the electron transport layer is described in detail.

[0028] like Figure 1 As shown, according to an embodiment of the present invention, a low-temperature preparation method of TiO2 for perovskite solar cells is provided. 2 The method of an electron transport layer comprises the following steps:

[0029] Step S1: Cleaning the conductive glass substrate, the FTO (fluorine-doped tin oxide) conductive glass is ultrasonically cleaned with deionized water, isopropanol and ethanol in sequence, and then dried with nitrogen to obtain a clean FTO conductive glass substrate. Optionally, the ultrasonic cleaning with deionized water, isopropanol and ethanol can be performed once, and each cleaning lasts for 30 minutes.

[0030] Step S2: Place the clean FTO conductive glass substrate under the ultraviolet lamp (UV lamp) of the ultraviolet ozone surface treatment equipment for irradiation treatment to form a hydrophilic surface, thereby obtaining the FTO conductive glass substrate cleaned by ultraviolet ozone. Optionally, the irradiation treatment lasts for 30 minutes.

[0031] Step S3: weigh the materials, prepare a titanium dioxide precursor solution, add titanium sulfate to clean deionized water to obtain a titanium dioxide water bath precursor solution, and place the prepared titanium dioxide water bath precursor solution in a beaker. The obtained titanium dioxide water bath precursor solution is used for subsequent steps. Optionally, the concentration of the prepared titanium dioxide water bath precursor solution is 0.04 mol / L to 0.2 mol / L.

[0032] Step S4: Lay the FTO conductive glass substrate cleaned by UV ozone flat in a culture dish, and then slowly pour the titanium dioxide water bath precursor solution into the culture dish until the FTO conductive glass substrate is immersed therein.

[0033] Step S5: Place the culture dish containing the FTO conductive glass substrate in an oven for reaction to obtain a uniform TiO 2Electron transport layer. Optionally, the reaction temperature in the oven is 30°C to 100°C, and the reaction time is 30 minc to 90 min.

[0034] Step S6: Take the culture dish out of the oven and place the 2 The FTO conductive glass substrate sample of the electron transport layer was taken out from the culture dish, rinsed with deionized water and ethanol in turn, and then dried with nitrogen gas to obtain the final TiO 2 Electron transport layer.

[0035] In order to better understand the present invention, the following examples are provided by way of example to illustrate the low-temperature preparation of TiO2 for perovskite solar cells according to an embodiment of the present invention. 2 The method of the electron transport layer is further specifically described, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the scope of protection of the present invention.

[0036] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0037] Example 1

[0038] A low-temperature preparation of TiO for perovskite solar cells 2 Method for electron transport layer, wherein TiO 2 The electron transport layer is based on titanium sulfate hydrolysis and specifically includes the following steps.

[0039] Step S1, cleaning the conductive glass substrate: the FTO conductive glass is ultrasonically cleaned with deionized water, isopropanol, and ethanol in sequence for 30 minutes each time, and then dried with nitrogen to obtain a clean FTO conductive glass substrate.

[0040] Step S2: Place the clean FTO conductive glass substrate under a UV lamp of an ultraviolet ozone surface treatment device for 30 minutes to form a hydrophilic surface.

[0041] Step S3, preparing a titanium dioxide precursor solution: adding titanium sulfate to clean deionized water to obtain a titanium dioxide water bath precursor solution with a concentration of 0.04-0.2 mol / L for standby use.

[0042] Step S4, laying the FTO conductive glass substrate after UV ozone cleaning in a culture dish, and then slowly pouring the titanium dioxide water bath precursor solution into the beaker, and immersing the FTO conductive glass substrate in the titanium dioxide water bath precursor solution.

[0043] Step S5: Place the culture dish in an oven for reaction at a temperature of 30°C to 100°C for a reaction time of 30 to 90 minutes to obtain uniform TiO2 Electron transport layer.

[0044] Step S6: Take the culture dish out of the oven, take out the reacted FTO sample from the culture dish, rinse it with deionized water and ethanol in turn, blow it dry with nitrogen after rinsing, and dry it to obtain the final TiO 2 Electron transport layer.

[0045] In this example, the final TiO 2 The process of preparing perovskite thin films with electron transport layers is as follows.

[0046] 1) Configure 1.1M CsPbI 3 Precursor solution, the solvent is DMF.

[0047] 2) In the presence of TiO 2 Spin coating CsPbI on FTO conductive glass substrate as electron transport layer 3 Precursor solution, rotation speed is 2000rpm, time is 20s.

[0048] 3) The substrate after spin coating was placed on a heating platform at 220° C. for annealing for 15 minutes to obtain a perovskite film.

[0049] 4) Preparation of carbon electrode: Apply commercial carbon slurry on the surface of perovskite film to prepare a structure of FTO / TiO2 / CsPbI 3 Carbon-based perovskite solar cells with an effective light-active area of ​​0.0625 cm 2 .

[0050] So far, TiO was prepared based on the hydrolysis of titanium sulfate. 2 The perovskite solar cell with electron transport layer is completed.

[0051] The battery performance test of the device obtained in Example 1 is shown in Table 1 below. It can be concluded that the photoelectric conversion efficiency of the device obtained in Example 1 is 18.77%, the open circuit voltage is 1.112 V, and the short circuit current density is 20.51 mA / cm 2 , the filling factor is 0.823.

[0052] Comparative Example 1

[0053] A TiO2 for perovskite solar cells 2 Preparation of electron transport layer, TiO 2 The electron transport layer is based on the conventional hydrolysis of titanium tetrachloride, and the specific process is as follows.

[0054] Step 1: Clean the conductive glass substrate: The FTO conductive glass is ultrasonically cleaned with deionized water, isopropanol, and ethanol in sequence for 30 minutes each time. After cleaning, it is blown dry with nitrogen to obtain a clean conductive glass substrate.

[0055] Step 2: Preparation of titanium dioxide electron transport layer:

[0056] 1) Prepare titanium dioxide precursor solution: add titanium tetrachloride to a clean deionized ice-water mixture to obtain a titanium dioxide water bath precursor solution with a concentration of 0.2 mol / L for standby use;

[0057] 2) Place the clean FTO substrate under UV light of an ultraviolet ozone surface treatment device for 30 minutes to form a hydrophilic surface;

[0058] 3) Lay the FTO substrate after UV ozone cleaning flat in a culture dish, then slowly pour the titanium dioxide water bath precursor solution into the beaker, and immerse the FTO substrate in the precursor solution;

[0059] 4) placing the culture dish in an oven for reaction at 70° C. for 55 min to obtain a titanium dioxide electron transport layer;

[0060] 5) Take the culture dish out of the oven, take out the reacted FTO sample from the culture dish, rinse it with deionized water, ethanol, and deionized water in sequence, blow it dry with nitrogen after rinsing, and dry it.

[0061] Step 3: Preparation of perovskite film:

[0062] 1) Configure 1.1M CsPbI 3 Precursor solution, solvent is DMF;

[0063] 2) In FTO / TiO 2 The precursor solution was spin-coated on the substrate at a speed of 2000 rpm for 20 s;

[0064] 3) After the spin coating is completed, the perovskite film is placed on a heating platform at 220° C. and annealed for 15 minutes to obtain a perovskite film.

[0065] 4. Preparation of carbon electrode: Scrape commercial carbon slurry on the surface of perovskite film to prepare FTO / TiO 2 / CsPbI 3 Carbon-based perovskite solar cells with an effective light-active area of ​​0.0625 cm 2 .

[0066] At this point, the perovskite solar cell with TiO2 electron transport layer prepared by hydrolysis of titanium tetrachloride has been completed.

[0067] The device obtained in Comparative Example 1 was subjected to a battery performance test. As shown in Table 1, it can be concluded that the photoelectric conversion efficiency of the device obtained in Comparative Example 1 is 17.74%, the open circuit voltage is 1.101 V, and the short circuit current density is 20.52 mA / cm 2 , the filling factor is 0.785.

[0068] Table 1 Device battery performance test results of Example 1 and Comparative Example 1

[0069]

[0070] Based on the above analysis, it can be seen that a method for preparing a TiO2 electron transport layer for perovskite solar cells at a low temperature provided in an embodiment of the present invention solves the violent hydrolysis process of titanium tetrachloride in the ordinary chemical water bath method, overcomes the problems of rough surface and poor interface contact of titanium dioxide film, protects acid-sensitive substrates from acid corrosion, significantly improves the filling factor and photoelectric conversion efficiency of perovskite solar cells, and has good commercial potential.

[0071] All the above optional technical solutions can be arbitrarily combined to form optional embodiments of the present application, which will not be described one by one here.

[0072] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0073] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a TiO2 electron transport layer for a perovskite solar cell at low temperature, characterized in that: The following steps are involved: Step S1: cleaning the FTO conductive glass to obtain a clean FTO conductive glass substrate; Step S2: placing the clean FTO conductive glass substrate under the ultraviolet lamp of the ultraviolet ozone surface treatment equipment for irradiation treatment to form a hydrophilic surface, thereby obtaining the FTO conductive glass substrate after ultraviolet ozone cleaning; Step S3: preparing a titanium dioxide precursor solution, adding titanium sulfate into clean deionized water to obtain a titanium dioxide water bath precursor solution; Step S4: Lay the FTO conductive glass substrate after UV ozone cleaning flat in a culture dish, and then slowly pour the titanium dioxide water bath precursor solution into the culture dish until the FTO conductive glass substrate is immersed therein; Step S5: placing the culture dish containing the FTO conductive glass substrate in an oven for reaction to obtain a uniform TiO2 electron transport layer on the FTO conductive glass substrate; Step S6: Take the culture dish out of the oven, take the FTO conductive glass substrate with the TiO2 electron transport layer out of the culture dish, rinse it with deionized water and ethanol in sequence, and then blow it dry with nitrogen to obtain the final TiO2 electron transport layer.

2. The method for preparing a TiO2 electron transport layer for a perovskite solar cell at low temperature according to claim 1, characterized in that: The step S1 specifically includes: The FTO conductive glass was ultrasonically cleaned with deionized water, isopropanol and ethanol in sequence, and then dried with nitrogen to obtain a clean FTO conductive glass substrate.

3. The method for preparing a TiO2 electron transport layer for a perovskite solar cell at low temperature according to claim 1, characterized in that: The concentration of the titanium dioxide water bath precursor solution prepared in step S3 is 0.04 mol / L to 0.2 mol / L.

4. The method for preparing a TiO2 electron transport layer for a perovskite solar cell at low temperature according to claim 1, characterized in that: In the reaction of step S5, the temperature in the oven is set to 30° C. to 100° C., and the reaction time is set to 30 minc to 90 min.

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