Transparent conductive layer of perovskite solar cell and perovskite solar cell

Abstract

The invention relates to a transparent conductive layer of a perovskite solar cell and the perovskite solar cell, the perovskite solar cell comprises a hole transport layer, a light absorption layer and an electron transport layer which are stacked, holes generated by the light absorption layer are led out by the hole transport layer, and generated electrons are led out by the electron transport layer. The transparent conducting layer is arranged on the side, back to the light absorption layer, of the hole transmission layer or / and the side, back to the light absorption layer, of the electron transmission layer, holes or electrons are collected and transmitted through the transparent conducting layer, the transparent conducting layer comprises IZO layers and ITO layers which are alternately arranged, the sum of the stacking number of the IZO layers and the stacking number of the ITO layers is n, and n is larger than or equal to 3. The arrangement is beneficial to reducing the square resistance of the transparent conductive layer and increasing the current.

Description

Technical Field

[0001] The present invention relates to a transparent conductive layer of a perovskite solar cell and a perovskite solar cell, belonging to the field of photovoltaics. Background Art

[0002] As a clean energy source, solar energy can meet the growing global energy demand. Among many optoelectronic devices, perovskite solar cells have attracted much attention due to their high photoelectric conversion efficiency and low manufacturing cost. The theoretical efficiency limit of a single-junction perovskite solar cell is about 31%, and the current record efficiency in the laboratory is 27.3%. According to the calculation of the Photovoltaic Association, for every 1% absolute increase in the efficiency of a photovoltaic cell, its levelized cost of electricity (LCOE) decreases by 5 - 7%. Therefore, improving the absolute efficiency of the cell is crucial for cost reduction in the photovoltaic industry.

[0003] In addition, although great progress has been made in the efficiency of perovskite cells, their device lifetime (or stability) is currently the bottleneck restricting the commercialization of perovskite cells. Compared with the service life of 20 - 30 years for crystalline silicon cells, the life of perovskite is generally considered to be within 5 years, and some literature estimates that the service life of perovskite is only 2 - 3 years. At this service life, the levelized cost of electricity of the device will lag far behind that of commercial silicon cells. Therefore, improving the stability and photoelectric efficiency of perovskite cells is the top priority for promoting the commercialization of perovskite cells. Summary of the Invention

[0004] In order to improve the stability and photoelectric efficiency of perovskite cells, the present invention provides a transparent conductive layer applicable to perovskite solar cells. This transparent conductive layer realizes the characteristics of low sheet resistance and high transmittance through the lamination of film layers of different materials, providing an innovative solution for high-efficiency optoelectronic devices. The stability is improved, and the performance limitations of preparing TCO under single layer and high temperature are broken through.

[0005] The technical solution adopted by the present invention is as follows: A transparent conductive layer of a perovskite solar cell, where the transparent conductive layer is provided on the perovskite solar cell as a functional layer. Here, the functional layer refers to a structural layer provided to achieve a certain function, and may have one or more functions such as increasing transmittance, adjusting spectral properties, and reducing sheet resistance in addition to conductivity. The perovskite solar cell in the present invention includes a stacked hole transport layer, a light absorption layer, an electron transport layer, and the transparent conductive layer is provided on the side of the hole transport layer facing away from the light absorption layer, or on the side of the electron transport layer facing away from the light absorption layer, or on both sides of the hole transport layer and the electron transport layer facing away from the light absorption layer. The transparent conductive layer in the present invention includes alternately arranged IZO layers and ITO layers. The thicknesses of different IZO layers can be the same or different, and the thicknesses of different ITO layers can be the same or different. The sum of the number of stacked IZO layers and ITO layers is n, where n≥2, and preferably n≥3.

[0006] The perovskite solar cell can be a multi-junction cell. When named according to the position of the electrodes, the electrodes of the perovskite solar cell include a top electrode and a bottom electrode. The top electrode is the electrode on the incident light side, and the bottom electrode is the electrode on the backlight side. When named according to the type of carriers received by the electrodes, the electrodes of the perovskite solar cell include a first electrode and a second electrode. The first electrode is the electrode that receives the carriers derived from the hole transport layer, and the second electrode is the electrode that receives the carriers derived from the electron transport layer. The names of the electrodes will be used according to needs in the following text. The first electrode is directly attached to the hole transport layer or indirectly attached through other layers. The second electrode is directly attached to or indirectly attached to the electron transport layer through other layers. The holes generated in the light-absorbing layer under the light-excitation state are extracted by the hole transport layer and transmitted to the first electrode, and the generated electrons are extracted by the electron transport layer and exported to the second electrode. The transparent conductive layer is disposed between the hole transport layer and the first electrode or between the electron transport layer and the second electrode, and can also be disposed between the hole transport layer and the first electrode and between the electron transport layer and the second electrode. The holes or electrons are collected through the transparent conductive layer and then transmitted to the corresponding electrode.

[0007] The thickness design of each structural layer affects the spectral properties passing through the transparent conductive layer and also affects the sheet resistance. As a preference, the total thickness of the stacked IZO layer and ITO layer is 40 - 200 nm. The thickness of the ITO layer is 15 - 20 nm, and the thickness of the IZO layer is 5 - 10 nm.

[0008] In the normal structure, the transparent conductive layer is preferably disposed between the top electrode and the electron transport layer. In the inverted structure, the transparent conductive layer is preferably disposed between the top electrode and the hole transport layer. Of course, in addition to being disposed at the top electrode, it can also be disposed at the bottom electrode to increase the carrier transport efficiency.

[0009] The preparation process of the transparent conductive layer not only affects the performance of the film layer itself, but also affects the performance of the light-absorbing layer and the carrier transport layer. In the present invention, the magnetron sputtering process is preferably used for coating. During the magnetron sputtering process, the present invention preferably introduces argon, oxygen, and argon-hydrogen mixed gas into the cavity. When electrons fly towards the substrate, they collide with argon atoms, causing them to ionize and generate argon ions and new electrons. Under the action of the electric field, the argon ions fly rapidly towards the cathode target, causing the target material to sputter. The role of the argon-hydrogen mixed gas is to neutralize excessive oxygen atoms and reduce the sheet resistance. The ratio of each gas in the mixed gas affects the sheet resistance of the deposited film layer. In the present invention, for the IZO layer, argon, oxygen, and argon-hydrogen mixed gas (Ar / H2) are preferably used. The total amount of gas introduced varies according to different target material. In the IZO, the volume ratio of hydrogen in the argon-hydrogen mixed gas is 2.10%-2.40%. The gas ratio of the different gases Ar:O2:Ar / H2 introduced is 15-25:0.5-1.5:45-55. In the ITO layer, the volume ratio of hydrogen in the argon-hydrogen mixed gas is 2.14%-2.40%. The ratio of the different gases Ar:O2:Ar / H2 introduced is 15-25:0.5-1.5:45-55. Further preferably, in the present invention, for the IZO layer, the volume ratio of hydrogen in the argon-hydrogen mixed gas is 2.40%, and the total gas introduction amount of argon, oxygen, and argon-hydrogen mixed gas is about 50 sccm. In the ITO layer, the volume ratio of hydrogen in the argon-hydrogen mixed gas is 2.14%, and the total gas introduction amount of argon, oxygen, and argon-hydrogen mixed gas is about 70 sccm.

[0010] The present invention will also provide perovskite solar cells prepared using the above transparent conductive layer, including but not limited to silicon-calcium tandem cells and calcium-calcium tandem cells. If the cell is a silicon-calcium tandem cell, the silicon cell is the bottom cell and the perovskite cell is the top cell. If the perovskite cell is a normal structure, the transparent conductive layer is disposed between the hole transport layer and the top electrode. If the perovskite cell is a reverse structure, the transparent conductive layer is disposed between the electron transport layer and the top electrode. If the cell is a calcium-calcium tandem cell, the transparent conductive layer can be disposed on the perovskite cell of the bottom cell, or on the perovskite cell of the top cell, or between the top cell and the bottom cell, or both on the top cell and the bottom cell. Taking the case where it is disposed on the perovskite cell of the top cell as an example, if the top cell structure is a reverse structure, the transparent conductive layer is disposed between the electron transport layer and the top electrode. If the top cell structure is a normal structure, the transparent conductive layer is disposed between the hole transport layer and the top electrode. In the tandem cell, the top electrode is disposed on the top cell, and the bottom electrode can be disposed on the bottom cell. The top electrode and the bottom electrode correspond to the first electrode and the second electrode in sequence, or the top electrode and the bottom electrode correspond to the second electrode and the first electrode in sequence.

[0011] As a preference, the perovskite solar cell includes a substrate, a hole transport layer, a light-absorbing layer (perovskite layer), an electron transport layer, a transparent conductive layer, and an electrode which are arranged in sequence. The materials for the hole transport layer are NiOx, CuSCN, PTAA, etc.; the materials for the electron transport layer are TiO2, SnO2, ZnO, etc.; and the materials for the electrode are silver, copper, or a silver-copper mixture.

[0012] The beneficial effects of the present invention include: in the present invention, ITO and IZO are stacked in an alternating manner as the transparent conductive layer. By using the film structures of different materials, the adhesion degree of the film can be increased, making the film more compact.

[0013] In the present invention, the transparent conductive layer overcomes the need for high-temperature annealing of a single-layer film through a multi-layer film design, enabling low-temperature annealing. An amorphous film structure can be formed at room temperature, which can increase the adhesion degree of the film and make the film more compact.

[0014] In the present invention, the interaction between films of different materials can reduce the sheet resistance of the film, increase the current of the solar cell, and make it more stable, thereby improving the efficiency of the solar cell.

[0015] In the present invention, by coordinating the number of film layers, the stacking order of film layers, and the thickness of film layers, the light transmittance of the transparent conductive layer is improved, the sheet resistance is reduced, and the current is increased.

[0016] In the preparation process of the ITO film and the IZO film layer in the present invention, an argon-hydrogen mixed gas is introduced to neutralize oxygen atoms, reduce the sheet resistance of the film layer, and increase the current and voltage of the solar cell by about 2%.

[0017] The surface of the transparent conductive layer formed by laminating multiple film layers in the present invention is smoother, which can better adhere to silver plating or MgF2. Description of the Drawings

[0018] Figure 1 Silicon-calcium stacked cell structure;

[0019] Figure 2 Jsc (short-circuit current density) test results of the cells in Example 1 and the cells in the comparative example;

[0020] Figure 3 Sheet resistance of the transparent conductive layer in Example 1 and the transparent conductive layer in the comparative example. Detailed Embodiments

[0021] The present invention will be described in a more specific form below, but it should not be construed that the protection scope of the present invention is limited by the following description. Unless otherwise specified, any range recited in the present invention includes the end values and any numerical value between the end values, as well as any sub-range constituted by any numerical value between the end values or the end values. For all raw materials of the present invention, there is no particular limitation on their purity, and the present invention preferably uses analytical grade. For all raw materials of the present invention, their sources and abbreviations are all conventional sources and abbreviations in the art, and are clear and definite in the fields related to their relevant uses. Those skilled in the art can purchase them from the market or prepare them by conventional methods according to the abbreviations and the corresponding uses.

[0022] "At least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the front and rear associated objects. "At least one (item)" or its similar expression means any combination of these items, including any combination of a single item or plural items. For example, at least one (item) of a, b or c can represent: a, b, c, the combination of a and b, the combination of a and c, the combination of b and c, or the combination of a, b and c, where a, b and c can be single or plural.

[0023] Those skilled in the art will understand that a perovskite solar cell is a battery that generates electricity using a material with a perovskite structure. The perovskite material is represented by the general formula [A][B][X]3, where [A] is at least one monovalent cation, [B] is at least one divalent cation, and [X] is at least one anion.

[0024] The perovskite solar cell includes a light-absorbing layer, a hole transport layer, an electron transport layer, and electrodes. The light-absorbing layer is mainly composed of perovskite materials and is used for generating photo-generated electrons. The hole transport layer and the electron transport layer are used to separate the holes and electrons generated by the light-absorbing layer. The electrodes include a first electrode and a second electrode. The first electrode is disposed on the side of the hole transport layer facing away from the light-absorbing layer, and the second electrode is disposed on the side of the electron transport layer facing away from the light-absorbing layer. The transparent conductive layer proposed in the present invention is disposed between the hole transport layer and the first electrode or between the electron transport layer and the second electrode. The transparent conductive layer functions to collect carriers and transport the carriers to the conductive layer, while ensuring the light transmittance. In the present invention, the transparent conductive layer includes an ITO layer (indium tin oxide) and an IZO layer (indium zinc oxide). ITO has good conductivity. By optimizing the deposition process and subsequent annealing treatment, its resistivity can be reduced, and it has excellent visible light transmittance. However, ITO deposited at low temperature (<150 °C) is usually polycrystalline with obvious grain boundaries. The ITO thin film deposited at room temperature or low temperature is often amorphous or microcrystalline, with high resistivity, poor stability, and rough surface. While IZO can still form a highly stable, uniform, and smooth amorphous thin film when deposited at room temperature or very low temperature (even below 100 °C). The amorphous IZO thin film has almost no grain boundaries, so the surface is extremely smooth, and the roughness can usually be controlled below 1 nm. The amorphous structure has no brittle grain boundaries, so that the resistivity of the IZO thin film changes little when it is repeatedly bent, stretched, or even folded. When these two material layers are alternately stacked in a certain order and the total number of layers is three or more, on the one hand, the advantages of the two materials can be combined, and on the other hand, the sheet resistance of the transparent conductive layer can be reduced, the transmittance of the thin film can be increased, and the battery efficiency can be improved. The interface compatibility between ITO and IZO is good, which increases the carrier migration path on the one hand and reduces the interface scattering on the other hand, realizing lattice matching.

[0025] In the present invention, the ITO layer and the IZO layer preferably adopt a magnetron sputtering process to form a film. This film-forming process can form a dense nanometer film layer to ensure the uniformity of the film layer. The design of the multi-layer film further reduces the damage to the substrate during the magnetron process compared with the single-layer film, including the damage to the light absorption layer, the hole transport layer, the electron transport layer, etc. Moreover, low-temperature film formation can be achieved. The film layers in the perovskite battery are prone to decomposition or lattice change under high-temperature conditions, which affects the battery performance. And the higher the temperature, the greater the damage to the battery performance. The present invention solves this problem through the design of the multi-layer film and can achieve low-temperature film formation. The annealing temperature of the transparent conductive layer in the present invention can be 100 °C or below. The number of layers of the transparent conductive layer can be 3 layers, 4 layers, 5 layers, 9 layers, 12 layers, etc. The stacking order of ITO and IZO can be ITO layer, IZO layer, ITO layer, or IZO layer, ITO layer, IZO layer, or ITO layer, IZO layer, ITO layer, IZO layer, or IZO layer, ITO layer, IZO layer, ITO layer, or ITO layer, IZO layer, ITO layer, IZO layer, ITO layer, etc.

[0026] The transparent conductive layer in the present invention is applicable to silicon-calcium stacked solar cells or other solar cells containing perovskite-type light absorption materials. During use, it is preferred that the transparent conductive layer is connected to the top electrode, and light is incident on the light absorption layer through the transparent conductive layer from the top electrode. The design of the multi-layer structure is beneficial to adjusting the light transmittance of the transparent conductive layer and increasing the light utilization rate.

[0027] When the perovskite battery where the transparent conductive layer is located adopts a reverse structure, that is, a p-i-n structure, the top electrode is the second electrode, and the transparent conductive layer is arranged between the electron transport layer and the second electrode. It is preferred that the transparent conductive layer adopts a four-layer structure, such as IZO layer, ITO layer, IZO layer, ITO layer. The thickness of the ITO layer is 15-20 nm, and the thickness of the IZO layer is 5-10 nm. It is preferred that the thickness of each ITO layer is greater than that of any IZO layer. The following design can be adopted: from the side close to the electron transport layer to the side close to the second electrode, it is 5 nm IZO layer, 15 nm ITO layer, 10 nm IZO layer, 20 nm ITO layer, or 8 nm IZO layer, 15 nm ITO layer, 10 nm IZO layer, 18 nm ITO layer. The thickness of the ITO layer connecting the second electrode being greater than the IZO layer connecting the electron transport layer is beneficial to improving the light transmittance. Adopting the IZO layer to connect the electron transport layer is beneficial to matching the work function of carrier transport and reducing the electron transport barrier. The thickness of the ITO layer being greater than that of the IZO layer is beneficial to coordinating the sheet resistance and light transmittance of the transparent layer, ensuring the dominant position of ITO in terms of thickness design, utilizing the high mobility of IZO, and reducing the sheet resistance of the film layer. The synergistic effect of the number of stacked layers, the stacking order, and the thickness of each structural layer achieves the effects of reducing the sheet resistance, reducing the barrier, and increasing the transmittance.

[0028] In the present invention, both the ITO and IZO layers of the transparent conductive layer are formed by magnetron sputtering. During film formation, argon, oxygen, and argon-hydrogen mixed gas are introduced into the cavity. When electrons collide with argon atoms during their flight towards the substrate, they are ionized to produce argon ions and new electrons. The argon ions fly rapidly towards the cathode target under the action of an electric field, causing sputtering of the target material. Among the sputtered particles, neutral target atoms and molecules are deposited on the substrate to form a thin film. During this process, the substrate moves back and forth multiple times to deposit a film layer of the required thickness. The gas types in sputtering are argon, oxygen, and argon-hydrogen mixed gas (argon: hydrogen = 97%: 3%). The concentration relationship of each component in the mixed gas affects the sheet resistance and transmittance of the film layer. Reducing the sheet resistance and increasing the transmittance are beneficial to improving the current. As the oxygen flow rate increases, In is fully oxidized, resulting in a decrease in oxygen vacancies in the thin film. At the same time, the oxidation of doped tin occurs, reducing the carrier concentration. The carrier concentration decreases with the increase in oxygen flow rate, thus deteriorating the conductivity. In the present invention, doping argon-hydrogen mixed gas into the mixed gas is beneficial to neutralizing excessive oxygen atoms and reducing the sheet resistance. During implementation, when depositing the IZO film layer, the total flux of the mixed gas is 70 sccm (the hydrogen doping ratio in Ar / H2 gas is 2.10% - 2.30%), and when depositing the ITO film layer, the total amount of gas introduced is 50 sccm (the hydrogen doping ratio in Ar / H2 gas is 2.14% - 2.35%).

[0029] When the perovskite battery in the present invention is a silicon-calcium tandem battery, the perovskite serves as the top cell and the silicon cell serves as the bottom cell. The battery structure is the first electrode, silicon cell, hole transport layer, light absorption layer, electron transport layer, transparent conductive layer, and second electrode. Both the first electrode and the second electrode are metal electrodes, and the second electrode is a metal grid line provided on the transparent conductive layer. When the perovskite battery in the present invention is a calcium-calcium tandem battery, the wide-bandgap perovskite serves as the top cell and the narrow-bandgap perovskite serves as the bottom cell. The battery structure is: the first electrode, narrow-bandgap perovskite battery, hole transport layer, light absorption layer, electron transport layer, transparent conductive layer, and second electrode. Both the first electrode and the second electrode are metal electrodes, and the second electrode is a metal grid line provided on the transparent conductive layer.

[0030] The following is further described by way of specific examples.

[0031] Example 1

[0032] This example is a preparation method of a silicon-calcium tandem battery. The silicon cell serves as the bottom cell and the perovskite battery serves as the top cell. The perovskite battery has an inverted (p-i-n) structure, as Figure 1 , and the preparation method of this battery includes the following steps:

[0033] 1. Obtain Substrate 1

[0034] Using a silicon cell as a substrate, silicon wafers with a size of 25×25 mm are formed by cutting. A layer of ITO with a thickness of about 10 nm is deposited on the surface of the silicon cell as a tunneling layer, and then it is processed in an ultraviolet ozone processor to clean the surface of the silicon wafer. After 15 minutes of processing, it is set aside for use.

[0035] 2. Preparation of hole transport layer 2

[0036] Prepare a MeO-2PACz solution with ethanol as the solvent, and the solution concentration is 0.5 mg / ml; after filtering the solution to remove large particles, take 200 μl and drop it on the silicon wafer, and perform spin coating at a spin coating rate of 4000 rpm for 30 s. The spin coating is annealed at 120 °C for 10 min to obtain a MeO-2PACz hole transport layer with a thickness of about 3 nm.

[0037] 3. Preparation of light-absorbing layer 3

[0038] Prepare a perovskite solution

[0039] (1) a. Dissolve PbI2 (lead iodide), FAI (formamidinium iodide), PbBr2 (lead bromide), and FABr (formamidinium bromide) in a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) at a molar ratio of 0.75:0.75:0.25:0.25 to form Solution 1, where the volume ratio of DMF to DMSO is 5:1, and the concentration of Pb 2+ in Solution 1 is 1.7 mol / L;

[0040] b. Add a MACl additive to Solution 1 to form Solution 2, and the mass fraction of MACl in Solution 2 is 30%. c. Heat Solution 2 to 70 °C and stir for 70 min until completely dissolved;

[0041] d. Filter the solution using a 0.22 μm filter element to remove large particles in the solution and obtain the perovskite film layer solution.

[0042] (2) Spin coat the perovskite film layer solution on the hole transport layer at a spin coating rate of 4000 rpm. At the 15th second of spin coating, add 0.4 mL of the anti-solvent chlorobenzene dropwise on the film layer, and complete the dropwise addition within 2 s, and then continue spin coating for a total of 40 s.

[0043] (3) After the spin coating is completed, anneal in air at 145 °C for 20 min, and control the humidity at 20-30% to obtain a perovskite film layer with a thickness of about 500 nm.

[0044] 4. Preparation of electron transport layer 4

[0045] Use a vacuum evaporation device to evaporate C by thermal evaporation 60The material is formed on the perovskite film layer to form a 20nm electron transport layer, and the evaporation vacuum is 7*10 -4 Below Pa.

[0046] 5. Preparation of hole blocking layer 5

[0047] ALD atomic layer deposition equipment was used to form a 10 nm hole blocking layer on the electron transport layer by atomic layer deposition of SnO2.

[0048] 6. Preparation of transparent conductive layer 6

[0049] (1) Use magnetron sputtering equipment to place the silicon wafer obtained in step 5 into the fixture template. After fixing, place it into the magnetron sputtering machine, close the hatch and perform vacuum treatment. Wait until the vacuum degree is 6*10 -4 Pa, start the equipment and keep the temperature in the chamber at room temperature.

[0050] (2) Open the shut-off valve corresponding to the target position, fill the equipment with 40 sccm of argon-hydrogen mixed gas (argon-hydrogen ratio is 97:3), 1 sccm of oxygen and 10 sccm of argon. When the gas pressure in the chamber is constant, turn on the power switch and set the sputtering power to 1000 W. After preparation is completed, start the program and form a film layer of about 20 nm by sputtering the IZO target.

[0051] (3) After IZO sputtering is completed, temporarily turn off the IZO power supply, turn on the ITO power supply, set the sputtering power to 1200W, and start the program after confirming that the substrate movement position is correct. Fill the equipment with 50sccm of argon-hydrogen mixed gas (argon-hydrogen ratio is 97:3), 1sccm of oxygen and 20sccm of argon, and sputter about 10nm of ITO film through ITO. (4) After ITO sputtering is completed, turn off the ITO power supply, then turn on the IZO power supply, set the power to 1200W, reset the gas ratio, sputter about 20nm of IZO film, then turn off the power supply and turn off the gas switch. After the machine is shut down, remove the silicon wafer and the production is completed.

[0052] 7. Silver electrode 7 production:

[0053] Use evaporation equipment to evaporate silver electrodes on the finished source film. At this point, the laminated battery is completed.

[0054] Example 2

[0055] The only differences from Example 1 are that (1) the film structure of the transparent conductive layer is different, and (2) a MgF2 layer is provided on the transparent conductive layer. The steps for preparing the transparent conductive layer are as follows:

[0056] (1) Using a magnetron sputtering device, place the silicon wafer obtained in step 5 into the fixture template. After fixing, place it into the magnetron sputtering machine tool, close the chamber door for vacuum pumping. When the vacuum degree is below 6*10 -4 Pa, start the device and keep the chamber temperature at room temperature.

[0057] (2) Open the cut-off valve of the corresponding target position, fill the device with 30 sccm of argon-hydrogen mixed gas (argon-hydrogen ratio is 97:3), 1 sccm of oxygen and 10 sccm of argon. When the gas pressure in the chamber is constant, turn on the power switch, set the power sputtering power to 1000 W. After preparation, start the substrate running program, and form a film layer about 20 nm thick by sputtering the ITO target;

[0058] (3) After the ITO sputtering is completed, temporarily turn off the ITO power, turn on the IZO power, set the sputtering power to 1200 W. After determining that the substrate movement position is correct, start the substrate running program, fill the device with 40 sccm of argon-hydrogen mixed gas (argon-hydrogen ratio is 97:3), 1 sccm of oxygen and 10 sccm of argon, and sputter about 10 nm of IZO film layer;

[0059] (4) After the IZO sputtering is completed, turn off the IZO power, then turn on the ITO power, set the power to 1200 W, reset the gas ratio, sputter about 20 nm of ITO film, then turn off the power, close the gas switch. After the machine shuts down, take out the silicon wafer, and the production is completed.

[0060] (5) The preparation steps of the MgF2 layer are as follows: Place high-purity MgF2 particles in a tungsten boat or molybdenum crucible, heat to 1100 °C under 10 -4 -10 -6 Pa to sublime MgF2 into gas, and the MgF2 gas condenses into a film on the transparent conductive layer, about 90 nm. The silicon wafer after the MgF2 layer enters the next process - the production of silver electrodes.

[0061] Example 3

[0062] The difference from Example 1 is only that the structure of the transparent conductive layer is different. The transparent conductive layer from the side close to the electron transport layer to the side close to the electrode is successively a 5 nm IZO layer, a 15 nm ITO layer, a 10 nm IZO layer, and a 20 nm ITO layer, and then the electrode layer is prepared. The preparation method of the perovskite is the same as that in Example 1.

[0063] Comparative Example

[0064] The difference from Example 1 is only that the structure of the transparent conductive layer is different. In this comparative example, the transparent conductive layer only contains an IZO layer. The preparation method of the transparent conductive layer is as follows:

[0065] (1) Using a magnetron sputtering device, place the silicon wafer obtained in step 5 into the fixture template. After fixing, place it into the magnetron sputtering machine tool, close the chamber door for vacuum pumping. When the vacuum degree is below 6*10 -4 Pa, start the device and keep the chamber temperature at room temperature.

[0066] (2) Open the cut-off valve of the corresponding target position, fill the device with a mixed gas of argon and hydrogen (argon-hydrogen ratio is 97:3) at 40 sccm, oxygen at 1 sccm, and argon at 10 sccm. When the gas pressure in the chamber is constant, turn on the power switch, set the power sputtering power to 1000 W. After preparation, start the program and form a film layer of about 20 nm by sputtering the IZO target.

[0067] (3) After the IZO sputtering is completed, turn off the power and the gas switch. After the machine shuts down, take out the silicon wafer and the production is completed.

[0068] Test the sheet resistance and light transmittance of the transparent conductive layer in Examples 1-2 and the comparative example. The test method is as follows: Prepare a transparent conductive layer on a transparent SiO2 glass (light transmittance 99%) by the method in the example or the comparative example, and use a spectrophotometer to test the transmittance of the thin film in visible light (VL), infrared light (IR), and ultraviolet light (UV). The test results are shown in Table 1.

[0069] Table 1 Light transmittance of the transparent conductive layer in the examples and the comparative example

[0070] VL(%) IR(%) UV(%) Example 1 87.5 82.4 71.7 Example 2 85.2 80.3 80.9 Example 3 86.1 81.3 70.6 Comparative example 75 78 47.6

[0071] Test the sheet resistance of the transparent conductive layer through a four-probe tester, Figure 2 which are the sheet resistances of the transparent conductive layer prepared by the preparation method in Example 1 and the transparent conductive layer prepared by the preparation method in the comparative example. After several repeated tests, take the average value. The average sheet resistance in Example 1 is 179 Ω / sq, and the average sheet resistance in the comparative example is 124 Ω / sq. The sheet resistance of the transparent conductive layer prepared in Example 2 is 126 Ω / sq obtained by the same test method.

[0072] Test the short-circuit current density (J sc ) of the batteries obtained in Example 1 and the comparative example. The results of several repeated tests are as Figure 3 shown. After taking the average value, the short-circuit current density of Example 1 is 20.25 mA / cm 2 , and that of the comparative example is 19.6 mA / cm 2 . The short-circuit current density of Example 2 is 20.18 mA / cm 2 obtained by the same test method.

[0073] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A transparent conductive layer of a perovskite solar cell, characterized in that: The transparent conductive layer is disposed on a perovskite solar cell, and the perovskite solar cell further includes a stacked hole transport layer, a light absorption layer, and an electron transport layer. Holes generated by the light absorption layer are led out by the hole transport layer, and electrons generated are led out by the electron transport layer. The transparent conductive layer is disposed on a side of the hole transport layer facing away from the light absorption layer, and / or the transparent conductive layer is disposed on a side of the electron transport layer facing away from the light absorption layer. Holes or electrons are collected and transmitted through the transparent conductive layer. The transparent conductive layer includes alternately arranged IZO layers and ITO layers, and the sum of the stacking numbers of the IZO layers and the ITO layers is n, where n≥3.

2. The transparent conductive layer according to claim 1, wherein: The total thickness of the stacked IZO layers and ITO layers is 40 - 200 nm.

3. The transparent conductive layer according to claim 1, characterized in that: The total number of layers of the IZO layers and the ITO layers is 3 - 6 layers.

4. The transparent conductive layer of the perovskite solar cell according to claim 1, wherein: The transparent conductive layer is electrically connected to the top electrode, and the top electrode is a metal grid line.

5. The transparent conductive layer of the perovskite solar cell according to claim 4, characterized in that: A MgF2 layer is disposed between the transparent conductive layer and the metal grid line.

6. The transparent conductive layer of the perovskite solar cell according to claim 1 or 4, characterized in that: The transparent conductive layer is disposed between the hole transport layer and the top electrode, and the perovskite solar cell is a silicon-perovskite tandem cell.

7. The transparent conductive layer of the perovskite solar cell according to claim 1, wherein: The thickness of the ITO layer is 15 - 20 nm, and the thickness of the IZO layer is 5 - 10 nm.

8. The transparent conductive layer according to claim 1, wherein: The IZO layer in the transparent conductive layer is formed by magnetron sputtering. The IZO layer is formed in an atmosphere of argon, oxygen, and argon-hydrogen mixture. When depositing the IZO layer, the volume ratio of argon:oxygen:argon-hydrogen mixture is 8 - 10:0.5 - 1.5:35 - 45, and the volume fraction of hydrogen in the argon-hydrogen mixture is 2.10 - 2.40%.

9. The transparent conductive layer according to claim 1, characterized in that: The ITO layer in the transparent conductive layer is formed by magnetron sputtering. The ITO layer is formed in an atmosphere of argon, oxygen, and argon-hydrogen mixture. When depositing the ITO layer, the volume ratio of argon:oxygen:argon-hydrogen mixture is 15 - 25:0.5 - 1.5:45 - 55, and the volume ratio of hydrogen in the argon-hydrogen mixture is 2.14 - 2.40%.

10. A perovskite solar cell, characterized in that: There is provided a transparent conductive layer as described in any one of claims 1 to 9.

Images