A method for preparing TiO2 electron transport layer for perovskite solar cells at low temperature

Abstract

The application relates to a TiO2 electron transport layer preparation method for a perovskite solar cell, and belongs to the technical field of perovskite solar cell preparation. The method solves the problem that grain agglomeration is prone to occurring in the prior art, thereby limiting the performance improvement of the perovskite solar cell. The method comprises the following steps: cleaning FTO conductive glass; placing the clean FTO conductive glass substrate under the ultraviolet lamp of an ultraviolet ozone surface treatment device to perform irradiation treatment; configuring a titanium dioxide precursor solution; laying the FTO conductive glass substrate treated by ultraviolet ozone cleaning in a culture dish, then slowly pouring the titanium dioxide water bath precursor liquid into the culture dish until the FTO conductive glass substrate in the culture dish is immersed; placing the culture dish containing the FTO conductive glass substrate in an oven to react, so that a uniform TiO2 electron transport layer is obtained on the FTO conductive glass substrate; taking out the FTO conductive glass substrate with the TiO2 electron transport layer, sequentially washing the FTO conductive glass substrate with deionized water and ethanol, then blowing dry nitrogen to obtain the final TiO2 electron transport layer.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell fabrication technology, specifically to a method for preparing a TiO2 electron transport layer for perovskite solar cells at low temperature. Background Technology

[0002] Metal halide perovskite solar cells have attracted widespread attention in recent years due to their advantages such as high photoelectric conversion efficiency, solution-based fabrication, and low cost. The structure of a perovskite solar cell mainly includes: a transparent conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a counter electrode. Compared to mesoporous perovskite solar cells, planar perovskite solar cells have significant application potential in flexible and tandem devices. In planar perovskite solar cells, the most commonly used inorganic electron transport layer materials are TiO2, SnO2, and ZnO.

[0003] TiO2, as an n-type semiconductor, is commonly used as an electron transport layer material due to its numerous advantages, such as a compatible energy level structure with perovskite, a large band gap, wide light transmittance in the ultraviolet and visible light regions, and low fabrication cost. The fabrication method and structural morphology of the TiO2 electron transport layer significantly influence the performance of solar cell devices. Currently, common methods for fabricating electron transport layers include thermal evaporation, electron beam evaporation, atomic layer deposition, magnetron sputtering, spin coating, and chemical bath methods. Among these, the chemical bath method offers advantages such as simple process, low fabrication temperature, and film formation retention, making it highly compatible with the fabrication process of perovskite solar cells.

[0004] The current mainstream chemical bath method prepares the TiO2 electron transport layer through the hydrolysis of TiCl4. However, this process involves vigorous hydrolysis and nucleation crystallization, which easily leads to grain agglomeration and the generation of oxygen vacancy defects. This results in low electron mobility of titanium dioxide and affects the interfacial contact with the perovskite film, limiting the improvement of perovskite solar cell performance. In addition, the low pH value caused by the strong acid (HCl) in the chemical bath limits the application of this chemical bath method on acid-sensitive substrates (such as flexible transparent conductive oxide (TCO) and ITO).

[0005] Therefore, this technical field needs an electron transport layer preparation method that can limit grain agglomeration to improve the performance of perovskite solar cells and overcome the effects of strong acids in chemical baths. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a method for preparing a TiO2 electron transport layer for perovskite solar cells at low temperatures. The purpose is to regulate the deposition process of titanium dioxide prepared by chemical bath, moderate the hydrolysis rate, and control the nucleation and growth of titanium dioxide grains. This aims to solve problems such as titanium dioxide grain agglomeration and poor interfacial contact performance with the perovskite film, thereby improving the photoelectric conversion efficiency of perovskite solar cells.

[0007] According to an embodiment of the present invention, a method for preparing a TiO2 electron transport layer for perovskite solar cells at low temperature is provided, comprising the following steps:

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

[0009] Step S2: Place 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, and obtain the FTO conductive glass substrate after ultraviolet ozone cleaning.

[0010] Step S3: Prepare a titanium dioxide precursor solution by adding titanium sulfate to clean deionized water to obtain a titanium dioxide water bath precursor solution.

[0011] Step S4: Spread the FTO conductive glass substrate, which has been cleaned by UV ozone, in a petri dish, and then slowly pour the titanium dioxide water bath precursor solution into the petri dish until the FTO conductive glass substrate is submerged.

[0012] Step S5: Place the petri dish containing the FTO conductive glass substrate in an oven for reaction, and obtain a uniform TiO2 electron transport layer on the FTO conductive glass substrate.

[0013] Step S6: Remove the petri dish from the oven, remove the FTO conductive glass substrate with the TiO2 electron transport layer from the petri 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.

[0014] Optionally, step S1 specifically includes: ultrasonically cleaning the FTO conductive glass sequentially with deionized water, isopropanol and ethanol, and then drying it with nitrogen gas 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 step S5, the temperature in the oven is set to 30℃~100℃, and the reaction time is set to 30min~90min.

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

[0018] (1) The titanium sulfate used is cheaper than the titanium tetrachloride used in the prior art, the preparation process is safer, and 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 interfacial 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, which enhances interfacial charge transport and improves battery efficiency.

[0021] (4) The operation process is simple, the materials are fully utilized, and it is easy to produce on a large scale. It has greater potential in the preparation of perovskite solar cells, with 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 layer, it is feasible to control the deposition process of titanium dioxide to achieve controllable growth and uniform coverage of high-quality TiO2 film, and protect the indium tin oxide (ITO) substrate from acid corrosion, thereby promoting the manufacturing of high-performance perovskite solar cells. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used 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 accompanying drawings. The accompanying drawings are schematic and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a process flow diagram of a method for preparing a TiO2 electron transport layer for perovskite solar cells at low temperature according to an embodiment of the present invention. Detailed Implementation

[0025] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0027] The following describes in detail, with reference to the accompanying drawings, a method for preparing a TiO2 electron transport layer for perovskite solar cells at low temperature according to an embodiment of the present invention.

[0028] like Figure 1 As shown, a method for preparing a TiO2 electron transport layer for perovskite solar cells at low temperature according to an embodiment of the present invention includes the following steps:

[0029] Step S1: Clean the conductive glass substrate. The FTO (fluorine-doped tin oxide) conductive glass is ultrasonically cleaned sequentially with deionized water, isopropanol, and ethanol. After cleaning, it is dried with nitrogen gas to obtain a clean FTO conductive glass substrate. Optionally, the ultrasonic cleaning with deionized water, isopropanol, and ethanol can be performed once, with each cleaning lasting 30 minutes.

[0030] Step S2: Place the cleaned 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, thus obtaining the FTO conductive glass substrate after ultraviolet ozone cleaning. Optionally, this 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. This 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: Spread the UV-ozone cleaned FTO conductive glass substrate flat in a petri dish, and then slowly pour the titanium dioxide water bath precursor solution into the petri dish until the FTO conductive glass substrate is submerged.

[0033] Step S5: Place the petri dish containing the FTO conductive glass substrate in an oven for reaction, and obtain a uniform TiO2 electron transport layer on the FTO conductive glass substrate. Optionally, the reaction temperature in the oven is 30℃~100℃, and the reaction time is 30min~90min.

[0034] Step S6: Remove the petri dish from the oven, remove the FTO conductive glass substrate sample with TiO2 electron transport layer from the petri dish, rinse it with deionized water and ethanol in sequence, blow it dry with nitrogen gas after rinsing, and dry it to obtain the final TiO2 electron transport layer.

[0035] To better understand the present invention, the following examples further illustrate the method for preparing a TiO2 electron transport layer for perovskite solar cells at low temperature according to the embodiments of the present invention. However, this should not be construed as limiting the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are also considered to fall within the protection scope of the present invention.

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

[0037] Example 1

[0038] A method for preparing a TiO2 electron transport layer for perovskite solar cells at low temperature, wherein the TiO2 electron transport layer is based on titanium sulfate hydrolysis, specifically including the following steps.

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

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

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

[0042] Step S4: Spread the FTO conductive glass substrate, which has been cleaned by ultraviolet ozone, in a petri dish, and then slowly pour the titanium dioxide water bath precursor solution into the beaker, so that the titanium dioxide water bath precursor solution immerses the FTO conductive glass substrate.

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

[0044] Step S6: Remove the petri dish from the oven, remove the reacted FTO sample from the petri dish, rinse it with deionized water and ethanol in sequence, blow it dry with nitrogen gas after rinsing, and then dry it to obtain the final TiO2 electron transport layer.

[0045] In this example, the process of preparing a perovskite thin film using the final TiO2 electron transport layer obtained above is as follows.

[0046] 1) Prepare a 1.1M CsPbI3 precursor solution using DMF as the solvent.

[0047] 2) Spin-coat the CsPbI3 precursor solution onto an FTO conductive glass substrate with a TiO2 electron transport layer at a speed of 2000 rpm for 20 s.

[0048] 3) After spin coating, the substrate is placed on a heating table at 220°C and annealed for 15 minutes to obtain a perovskite film.

[0049] 4) Fabrication of carbon electrodes: A carbon-based perovskite solar cell with a structure of FTO / TiO2 / CsPbI3 / Carbon was prepared by coating a commercial carbon paste onto the surface of a perovskite thin film. The effective active area under light illumination was 0.0625 cm². 2 .

[0050] Thus, the fabrication of perovskite solar cells based on the preparation of TiO2 electron transport layers by titanium sulfate hydrolysis is completed.

[0051] Battery performance tests were performed on the device obtained in Example 1, as shown in Table 1 below. The results show that the device obtained in Example 1 has a photoelectric conversion efficiency of 18.77%, an open-circuit voltage of 1.112V, and a short-circuit current density of 20.51mA / cm². 2 The fill factor is 0.823.

[0052] Comparative Example 1

[0053] A method for preparing a TiO2 electron transport layer for perovskite solar cells is described, wherein the TiO2 electron transport layer is based on the conventional hydrolysis of titanium tetrachloride, and the specific process is as follows.

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

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

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

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

[0058] 3) Spread the FTO substrate after UV ozone cleaning in a petri dish, and then slowly pour the titanium dioxide water bath precursor solution into the beaker, so that the precursor solution immerses the FTO substrate.

[0059] 4) Place the petri dish in an oven for reaction at 70℃ for 55 min to obtain the titanium dioxide electron transport layer;

[0060] 5) Remove the petri dish from the oven, remove the reacted FTO sample from the petri dish, and rinse it in sequence with deionized water, ethanol, and deionized water. After rinsing, blow it dry with nitrogen gas and then dry it to obtain the final product.

[0061] Step 3: Preparation of perovskite thin films:

[0062] 1) Prepare a 1.1M CsPbI3 precursor solution using DMF as the solvent;

[0063] 2) Spin-coat the precursor solution onto the FTO / TiO2 substrate at a speed of 2000 rpm for 20 s;

[0064] 3) After spin coating, the perovskite film is placed on a heating stage at 220℃ for annealing for 15 minutes to obtain the perovskite film.

[0065] 4. Carbon electrode fabrication: A carbon-based perovskite solar cell with a structure of FTO / TiO2 / CsPbI3 / Carbon was prepared by coating a commercial carbon paste onto the surface of a perovskite thin film. The effective active area under light illumination was 0.0625 cm². 2 .

[0066] Thus, the fabrication of perovskite solar cells based on the preparation of TiO2 electron transport layers by the hydrolysis of titanium tetrachloride is completed.

[0067] The battery performance of the device obtained in Comparative Example 1 was tested, as shown in Table 1. The results show that the photoelectric conversion efficiency of the device in Comparative Example 1 is 17.74%, the open-circuit voltage is 1.101V, and the short-circuit current density is 20.52mA / cm². 2 The fill factor is 0.785.

[0068] Table 1. Battery performance test results of devices in Example 1 and Comparative Example 1

[0069]

[0070] Based on the above analysis, it can be seen that the method for preparing TiO2 electron transport layer for perovskite solar cells at low temperature according to the embodiments 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 interfacial contact of titanium dioxide thin film, protects acid-sensitive substrate from acid corrosion, and significantly improves the fill factor and photoelectric conversion efficiency of perovskite solar cells, thus having good commercial potential.

[0071] All of the above-mentioned optional technical solutions can be combined in any way to form the optional embodiments of this application, and will not be described in detail here.

[0072] It should be understood that the sequence number of each step in the above embodiments does not imply 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 embodiments of the present invention.

[0073] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a TiO2 electron transport layer for perovskite solar cells at low temperature, characterized in that, Includes the following steps: Step S1: Clean the FTO conductive glass to obtain a clean FTO conductive glass substrate; Step S2: Place 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, and obtain the FTO conductive glass substrate after ultraviolet ozone cleaning. Step S3: Prepare a titanium dioxide precursor solution by adding titanium sulfate to clean deionized water to obtain a titanium dioxide water bath precursor solution. Step S4: Spread the FTO conductive glass substrate, which has been cleaned by UV ozone, in a petri dish, and then slowly pour the titanium dioxide water bath precursor solution into the petri dish until the FTO conductive glass substrate is submerged. Step S5: Place the petri dish containing the FTO conductive glass substrate in an oven for reaction, and obtain a uniform TiO2 electron transport layer on the FTO conductive glass substrate. Step S6: Remove the petri dish from the oven, remove the FTO conductive glass substrate with the TiO2 electron transport layer from the petri 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. In step S5, the oven temperature is set to 30°C to 100°C, and the reaction time is set to 30 min to 90 min.

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

3. The method for preparing a TiO2 electron transport layer for perovskite solar cells 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.

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