Method for preparing electron transport layer, electron transport layer and solar cell

Abstract

The present invention discloses a method for preparing an electron transport layer, an electron transport layer and a solar cell. The method for preparing the electron transport layer comprises: providing a substrate; depositing TiO on the substrate by electron beam evaporation method; x Electron transport layer. The present invention prepares a high-quality electron transport layer by electron beam evaporation, which requires simple equipment and low cost, and can deposit and form a dense TiO x The thin film has improved uniformity, the efficiency of the perovskite solar cell device using it as an electron transport layer is improved, and the device stability is improved. The preparation process has excellent repeatability and is suitable for large-scale commercial production.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a method for preparing an electron transport layer, an electron transport layer and a solar cell. Background Art

[0002] Perovskite solar cells have attracted widespread attention in recent years. However, conventional perovskite solar cells are based on organic-inorganic hybrid perovskite materials (MAPbI 3 , FAPbI 3 Although organic-inorganic hybrid perovskite materials are highly efficient, their poor thermal stability due to their organic components limits their industrialization. All-inorganic perovskite materials have excellent thermal stability and compatibility with organisms, which enables related optoelectronic devices to have a stable and long-term basis for use. Therefore, all-inorganic perovskite materials have gradually become one of the current research hotspots.

[0003] The structure of perovskite solar cells mainly includes: substrate, electron transport layer, perovskite layer, hole transport layer and metal electrode. As an important component of perovskite solar cells, the electron transport layer has an important influence on the photoelectric conversion efficiency of perovskite solar cells. 2 As the electron transport layer, the perovskite solar cell shows good performance, but the general method for preparing the electron transport layer (including hydrothermal method, spin coating, spray pyrolysis method, etc.) is difficult to control the film thickness and uniformity, and there are a large number of defects on the film surface, which affects the interface between the electron transport layer and the perovskite layer, greatly limiting the photoelectric conversion efficiency of the perovskite solar cell and the life of the perovskite solar cell, and due to process reasons, it is also difficult to achieve large-scale preparation, which in turn affects its promotion and application. There are also magnetron sputtering and atomic layer deposition methods for preparing the electron transport layer. Although compared with the hydrothermal method, spin coating, and spray pyrolysis method, the film thickness can be controlled and the uniformity is relatively improved, the equipment is complex and the cost is high. Therefore, it is particularly important to develop a method for an electron transport layer that can accurately control the film thickness, has good uniformity, few film defects, low cost, and can be prepared on a large scale for the development of perovskite solar cells. Summary of the invention

[0004] The embodiments of the present invention provide a method for preparing an electron transport layer, an electron transport layer and a solar cell, so as to solve the problems in the prior art of preparing an electron transport layer, such as difficulty in controlling film thickness and uniformity, and complex equipment and high cost.

[0005] In one aspect, an embodiment of the present invention provides a method for preparing an electron transport layer, comprising:

[0006] Setting a substrate;

[0007] TiO was deposited on the substrate by electron beam evaporation. x Electron transport layer.

[0008] On the other hand, an embodiment of the present invention provides an electron transport layer, wherein the TiO x The electron transport layer is prepared by the above method.

[0009] On the other hand, an embodiment of the present invention provides a solar cell, comprising a substrate, a TiO x Electron transport layer, perovskite layer, hole transport layer and metal electrode, among which TiO x The electron transport layer is prepared by the above method.

[0010] The present invention provides a method for preparing an electron transport layer, an electron transport layer and a solar cell, which have the following advantages:

[0011] The electron beam evaporation method is used to prepare the electron transport layer. Not only is the equipment simple and the cost low, but also the grain size (i.e., film thickness) and uniformity of the electron transport layer can be improved by adjusting the preparation process parameters, reducing film defects, and improving the film quality of the electron transport layer, so as to improve the transmission efficiency of electrons and block the transport of holes, thereby improving the separation and transmission efficiency of electron-hole pairs, and thus improving the film-forming performance of the perovskite layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] 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 or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 A flow chart of a method for preparing an electron transport layer provided in an embodiment of the present invention;

[0014] Figure 2 A schematic diagram of the structure of a solar cell provided by an embodiment of the present invention;

[0015] Figure 3 The JV curve of the solar cell when the annealing temperature of the electron transport layer provided in the embodiment of the present invention is 0-600°C;

[0016] Figure 4 is the JV curve of the solar cell without electron transport layer;

[0017] Figure 5 is the JV curve of a solar cell with an electron transport layer prepared by spray pyrolysis;

[0018] Figure 6 is the JV curve of a solar cell with an electron transport layer prepared by spin coating;

[0019] Figure 7 JV curve of a solar cell with an electron transport layer prepared by a hydrothermal method. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Figure 1 A flowchart of a method for preparing an electron transport layer provided in an embodiment of the present invention. An embodiment of the present invention provides a method for preparing an electron transport layer, the method comprising:

[0022] S100, setting a substrate.

[0023] For example, FTO transparent conductive glass can be used as a substrate to prepare TiO x The substrate needs to be cleaned before the electron transport layer is formed. The cleaning method used includes ultrasonic cleaning with deionized water, acetone, and anhydrous ethanol for 20 minutes in sequence, and then drying with nitrogen.

[0024] S110, TiO is deposited on the substrate by electron beam evaporation x Electron transport layer.

[0025] For example, when depositing TiO x When the electron transport layer is Ti 3 O 5 、TiO 2 Particles or TiO 2 Powder is used as raw material, and the deposition rate is set to The deposition thickness is set to 0-1 μm, and the substrate needs to be heated to 0-800°C before deposition.

[0026] In the embodiment of the present invention, TiO is deposited in S110. x When the electron transport layer is TiO xThe electron transport layer is at least two layers, namely the first electron transport layer and the second electron transport layer, wherein the first electron transport layer is deposited on the substrate, and the second electron transport layer is deposited on the first electron transport layer. The difference between the first electron transport layer and the second electron transport layer is that the first electron transport layer is deposited in an oxygen-permeable environment and annealed after the deposition, while the second electron transport layer is subjected to at least one of no oxygen permeation and no annealing during the preparation process, except for TiO x In addition, the second electron transport layer can also use SnO 2 or In 2 O 3 Prepared.

[0027] Therefore, when TiO x When the electron transport layer adopts a two-layer structure, the second electron transport layer can be prepared by only passing oxygen but not annealing, or by only annealing without passing oxygen, or by neither passing oxygen nor annealing.

[0028] When TiO x When the electron transport layer adopts a three-layer structure, a third electron transport layer can be deposited on the second electron transport layer to form a third electron transport layer. The third electron transport layer is subjected to at least one of no oxygen permeation and no annealing during the preparation process. The oxygen permeation environment or annealing treatment of the third electron transport layer is different from that of the second electron transport layer, and except for TiO x In addition, the third electron transport layer can also be made of SnO 2 or In 2 O 3 For example, when the second electron transport layer is prepared by only passing oxygen without annealing, the third electron transport layer can be prepared by only annealing without passing oxygen, or by neither passing oxygen nor annealing. When the second electron transport layer is prepared by only annealing without passing oxygen, the third electron transport layer can be prepared by only passing oxygen without annealing, or by neither passing oxygen nor annealing. When the second electron transport layer is prepared by neither passing oxygen nor annealing, the third electron transport layer can be prepared by only passing oxygen without annealing, or by neither passing oxygen nor annealing.

[0029] In TiO x During the deposition of the electron transport layer, TiO xThe annealing temperature of the electron transport layer is set to 0-600°C, that is, after the first electron transport layer is deposited, the annealing temperature is 0-600°C. If the second electron transport layer or the third electron transport layer also needs annealing, the annealing temperature is also 0-600°C. At the same time, the oxygen flow rate is set to 0-500sccm, that is, during the deposition of the first electron transport layer, the oxygen flow rate is 0-500sccm. If the second electron transport layer or the third electron transport layer also needs oxygen, the oxygen flow rate is also 0-500sccm. During the deposition process, ion beam assisted deposition is performed throughout the process. After the deposition is completed, the prepared TiO x The electron transport layer film is placed in a tube furnace and annealed in an oxygen atmosphere for two hours. After natural cooling, TiO x Electron transport layer.

[0030] The present invention prepares a high-quality multi-electron transport layer by electron beam evaporation and applies it to perovskite solar cells. This method can deposit dense TiO 2 The uniformity of the thin film is improved, and the efficiency of the perovskite solar cell device using it as an electron transport layer is improved, and the device stability is improved. The preparation process has excellent repeatability and is suitable for large-scale commercial production. And the perovskite solar cell prepared using multiple electron transport layers is annealed at 0 to 600 ° C and oxygen-permeated TiO 2 The electron transport layer has a highly efficient electron transport function, and the electron transport layer that is not annealed and / or not oxygenated is in direct contact with the perovskite layer, which can inhibit the TiO 2 The photocatalytic effect on the perovskite layer improves the stability of the perovskite solar cell and thus increases its lifetime.

[0031] The embodiment of the present invention further provides an electron transport layer, which is prepared by the above method.

[0032] The embodiment of the present invention further provides a solar cell, such as Figure 2 As shown, the solar cell includes a substrate, a TiO x Electron transport layer, perovskite layer, hole transport layer and metal electrode, among which TiO x The electron transport layer is prepared by the above method.

[0033] For example, the substrate, TiO x The electron transport layer, perovskite layer, hole transport layer and metal electrode are arranged in sequence from bottom to top. The perovskite layer can be made of CsPbI 3-x Br x The solution can be prepared, the hole transport layer can be prepared by using spiro-OMeTAD material, and the metal electrode can be prepared by using Ag.

[0034] Specifically, CsPbI 3-x Br x The solution was prepared by: 3 , PbBr 2 The molar ratio of 3:2.85:0.15 was added to 1 ml of DMF and DMSO mixed solvent at a ratio of 9:1, and the mixture was placed on a magnetic stirrer and heated at 60 °C for 1 h until the solution was completely dissolved to obtain CsPbI 3-x Br x Perovskite solution.

[0035] In the preparation of CsPbI 3-x Br x After solution, in TiO x The perovskite solution was spin-coated on the electron transport layer. The specific process of the spin coater was as follows: first, the film was spin-coated at 1000 rpm for 10 seconds, then at 3000 rpm for 30 seconds, and then the film was immediately placed on a heating platform for annealing at 200 °C for 5 minutes to obtain CsPbI 3-x Br x Perovskite layer.

[0036] When preparing the hole transport layer, a layer of spiro-OMeTAD solution can be spin-coated on the perovskite layer at a speed of 7020 rpm to obtain the hole transport layer. Finally, a layer of Ag is evaporated on the hole transport layer using a thermal evaporation process to form a metal electrode, and finally the desired solar cell is obtained.

[0037] The voltage of the solar cell prepared by the method of the present invention is 0.839969V, and the short-circuit current density is 18.329591mA / cm 2 , the filling factor is 72.514528%, the photoelectric conversion efficiency is 11.164551%, and the JV curve is as follows Figure 3 As shown. The JV curve of the solar cell without electron transport layer, that is, the perovskite layer is directly spin-coated on the FTO transparent conductive glass is as follows Figure 4 Compared with spray pyrolysis ( Figure 5 ), spin coating ( Figure 6 )、Hydrothermal method( Figure 7 ) has greatly improved the performance of solar cells.

[0038] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0039] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing an electron transport layer, characterized in that: include: Setting a substrate; TiO is deposited on the substrate by electron beam evaporation x Electron transport layer; The TiO x Electron transport layer: Depositing a first electron transport layer on the substrate, wherein the first electron transport layer is deposited in an oxygen-permeable environment and annealed after the deposition; Depositing a second electron transport layer on the first electron transport layer, wherein the second electron transport layer is subjected to at least one of a treatment of not passing oxygen and not annealing during the preparation process; After the second electron transport layer is prepared, the method further comprises: A third electron transport layer is deposited on the second electron transport layer. The third electron transport layer is subjected to at least one of oxygen-free and non-annealing treatments during preparation, and the oxygen-free environment or annealing treatment of the third electron transport layer is different from that of the second electron transport layer.

2. The method for preparing an electron transport layer according to claim 1, characterized in that: After the deposition of the first electron transport layer is completed, the annealing temperature is 0-600° C. If the second electron transport layer or the third electron transport layer also needs annealing, the annealing temperature is also 0-600° C.

3. The method for preparing an electron transport layer according to claim 1, characterized in that: During the deposition of the first electron transport layer, the oxygen flow rate is 0-500 sccm. If the second electron transport layer or the third electron transport layer also needs to be ventilated with oxygen, the oxygen flow rate is also 0-500 sccm.

4. The method for preparing an electron transport layer according to claim 2, characterized in that: The first electron transport layer is prepared using Ti3O5, TiO2 particles or TiO2 powder as raw materials, and the second electron transport layer and the third electron transport layer are prepared using Ti3O5, TiO2 particles, TiO2 powder, SnO2 or In2O3.

5. An electron transport layer, characterized in that The electron transport layer is prepared by the method according to any one of claims 1 to 4.

6. A solar cell, characterized in that: Including substrate, TiO x An electron transport layer, a perovskite layer, a hole transport layer and a metal electrode, wherein the TiO x The electron transport layer is prepared by the method according to any one of claims 1 to 4.

7. A solar cell according to claim 6, characterized in that: The perovskite layer is coated on the TiO x The electron transport layer is formed and annealed.

8. A solar cell according to claim 7, characterized in that: The perovskite solution is obtained by sequentially adding HPIb3, PbBr2 and CsI into a mixed solvent of DMF and DMSO, and stirring and dissolving the mixture.

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