TCO film preparation method

Abstract

The invention discloses a TCO film preparation method, which comprises the following steps: sequentially carrying out H, N and O three-step annealing on a substrate on which a TCO target material is deposited, and through the sequential design of reduction-buffer-passivation, the H atmosphere can effectively activate oxygen vacancies to improve the carrier mobility of the TCO film, and the N atmosphere can improve the buffer environment to promote the grain growth in the annealing process, so that the TCO film is prepared. The cross contamination between H2 / O2 is prevented, and the passivation effect by using O2 atmosphere is improved, so that the conductivity, light transmittance and structural stability of the TCO film are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a method for preparing a TCO thin film used in the field of cells. Background Art

[0002] TCO (transparent conductive oxide) films are a key component of thin-film solar cells, exhibiting high light transmittance and low resistivity within the visible wavelength range. High transmittance within the visible spectrum improves photovoltaic cell conversion efficiency and reduces energy loss. The performance of TCO films significantly impacts the efficiency and lifespan of thin-film solar cells. Therefore, research and optimization of TCO films is crucial for improving the performance of thin-film solar cells.

[0003] Traditional TCO thin film fabrication methods struggle to achieve a balanced balance of conductivity, transmittance, and structural stability. Performance instability is particularly pronounced at low temperatures, hindering their application in devices such as thin-film transistors. Existing annealing methods lack precise control of the gas environment, often failing to effectively control oxygen vacancy and carrier concentrations. This results in poor film uniformity and high resistance, impacting device performance.

[0004] Therefore, developing a method that can simultaneously improve the conductivity, transmittance, and structural stability of TCO films has become a key research priority. Traditional annealing methods often struggle to optimize these properties simultaneously. Precisely controlling the gas environment during the annealing process to achieve comprehensive improvements in TCO film performance has become a pressing technical challenge. Summary of the Invention

[0005] To address the problem of the inability of conventional TCO thin film annealing processes to effectively control the gas environment and improve the conductivity, transmittance, and structural stability of TCO thin films, the present application discloses a TCO thin film preparation method, which sequentially performs H2, N2, and O2 annealing on a substrate after TCO target deposition. Through a "reduction-buffering-passivation" timing design, the H2 atmosphere can effectively activate oxygen vacancies and improve the carrier mobility of the TCO film. The N2 atmosphere improves the buffer environment, promotes grain growth during the annealing process, prevents cross-contamination between H2 / O2, and enhances the passivation effect of the O2 atmosphere, thereby improving the conductivity, transmittance, and structural stability of the TCO film.

[0006] To achieve the above object, the specific solutions provided by the present invention are as follows:

[0007] A method for preparing a TCO film comprises the steps of depositing a TCO target material on a substrate, and annealing the TCO film in H2, N2 and O2 atmospheres in sequence to obtain the TCO film.

[0008] In one embodiment, the substrate includes conductive glass and a battery structure.

[0009] In one embodiment, the battery structure includes a single-junction battery structure or a stacked battery structure.

[0010] In one embodiment, the annealing temperature of each atmosphere is 150-300° C., and the annealing time is 5-30 minutes.

[0011] In one embodiment, the gas flow rate introduced into the H2 atmosphere is 100-500 sccm.

[0012] In one embodiment, the gas flow rate introduced into the N2 atmosphere is 100-500 sccm.

[0013] In one embodiment, the gas flow rate introduced into the O2 atmosphere is 100-500 sccm.

[0014] In one embodiment, the TCO target material includes one of ITO (indium tin oxide), IZO (indium zinc oxide), AZO (aluminum-doped ZnO), GZO (gallium-doped ZnO), SnO2, ZnO, In2O3, ICO (cerium-doped indium oxide), and IWO (tungsten-doped indium oxide).

[0015] In one embodiment, the TCO film has a thickness of 5-200 nm.

[0016] In one embodiment, the TCO target is prepared by vacuum deposition, including the steps of placing the substrate in a vacuum environment and setting the vacuum degree to 5.0×10 -4 —1.0×10 -4 Pa, argon and oxygen were introduced to adjust the vacuum to 3.0×10 -1 Pa—8.0×10 -1 Pa, oxygen-argon percentage: 0.5%-10%, control the coating power to be 600-2000W, and deposit the TCO target material onto the substrate.

[0017] The application provides a TCO film preparation method, applied to the field of solar cells, by precisely controlling the gas atmosphere of the TCO film in the annealing process, using the gas atmosphere of H2, N2 and O2 to anneal the TCO film, effectively activating the oxygen vacancy concentration in the film by using H2 gas, improving the carrier mobility of the ITO film and improving the conductivity of the film; using N2 as a buffer treatment process to improve the stable heat treatment environment, promote grain growth and effectively maintain the structural stability of the film, while improving the light transmittance of the film; in the O2 annealing stage, by precisely controlling the atmosphere environment, the film stability and optical performance are synergistically improved through surface selective passivation. The application adopts a three-step gas atmosphere annealing regulation mechanism to comprehensively optimize the traditional annealing process, effectively improving the performance and structural stability of the film. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The X-ray diffraction analyzer of the crystalline property analysis diagram of Example 1 and Comparative Examples 1-3 in the application.

[0019] In which No. 1 is the crystalline property analysis diagram of Comparative Example 1;

[0020] No. 2 is the crystalline property analysis diagram of Comparative Example 2;

[0021] No. 3 is the crystalline property analysis diagram of Comparative Example 3;

[0022] No. 4 is the crystalline property analysis diagram of Example 1. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the application, not all the embodiments.

[0024] In the description of the application, unless otherwise specified, the meaning of "a plurality of" is two or more; the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", "vertical", "horizontal", "top", "bottom", "inner", "outer" are based on the orientations or positional relationships shown in the drawings, and are only for the purpose of facilitating the description of the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the application. In addition, the terms "first", "second", "third" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0025] The present application provides a method for preparing a TCO thin film, comprising the steps of: depositing a TCO target material on a substrate, and annealing in H2, N2, and O2 atmospheres in sequence to obtain a TCO thin film.

[0026] In one embodiment, the substrate comprises conductive glass and a battery structure. The preparation method can be applied to the conductive glass. After the TCO film is prepared, the battery carrier layer, light absorption layer, and other functional layers are sequentially prepared to ultimately form the entire battery device. When applied to a battery structure, the method can be applied to the buffer layer, carrier layer, and other structural layers after the light absorption layer, effectively improving the device's light absorption capacity and conductivity.

[0027] In one embodiment, the cell structure includes a single-junction cell structure or a stacked cell structure. The cell structure described herein includes any structure that does not have a top transparent electrode or metal cell. The single-junction cell structure may include a crystalline silicon cell or a perovskite cell structure. The stacked cell structure may include a crystalline silicon perovskite stacked cell structure.

[0028] In one embodiment, the annealing temperature of each atmosphere is 150-300°C, and the annealing time is 5-30 minutes. The effects of annealing in different atmospheres vary. Annealing in a H2 atmosphere can effectively reduce oxygen vacancies in the film, improve the carrier mobility of the TCO film, and enhance the conductivity of the film. Then, a N2 atmosphere is used for buffering the transition, providing a stable thermal treatment environment, promoting grain growth, and improving the stability of the film structure. At the same time, the N2 atmosphere can remove H2 residues and reduce H2 contamination during passivation in an O2 atmosphere, effectively improving the film passivation effect and film quality.

[0029] In one embodiment, the gas flow rate of the H2 atmosphere is 100-500 sccm. Preferably, the gas flow rate of the H2 atmosphere is 200 sccm, the annealing temperature is 200° C., and the annealing time is 30 min.

[0030] In one embodiment, the gas flow rate of the N2 atmosphere is 100-500 sccm. Preferably, the gas flow rate of the N2 atmosphere is 200 sccm, the annealing temperature is 250° C., and the annealing time is 30 min.

[0031] In one embodiment, the gas flow rate of the O2 atmosphere is 100-500 sccm. Preferably, the gas flow rate of the O2 atmosphere is 100 sccm, the annealing temperature is 150° C., and the annealing time is 10 min.

[0032] In one embodiment, the TCO target material includes one of ITO (indium tin oxide), IZO (indium zinc oxide), AZO (aluminum-doped ZnO), GZO (gallium-doped ZnO), SnO2, ZnO, In2O3, ICO (cerium-doped indium oxide), and IWO (tungsten-doped indium oxide).

[0033] Preferably, the TCO target material is ITO (indium tin oxide).

[0034] In one embodiment, the TCO film has a thickness of 5-200 nm.

[0035] In one embodiment, the TCO target is prepared by vacuum deposition, including the steps of placing the substrate in a vacuum environment and setting the vacuum degree to 5.0×10 -4 —1.0×10 -4 Pa, argon and oxygen were introduced to adjust the vacuum to 3.0×10 -1 Pa—8.0×10 -1 Pa, oxygen-argon percentage: 0.5%-10%, control the coating power to be 600-2000W, and deposit the TCO target material onto the substrate.

[0036] In one embodiment, the TCO target material may also be deposited onto the substrate surface by magnetron sputtering, chemical vapor deposition, or solution deposition.

[0037] The following specific embodiments and comparative examples are provided to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] Example 1

[0039] This embodiment provides a method for preparing a TCO thin film, comprising the following steps:

[0040] Step 1: Clean a conductive glass.

[0041] Step 2: Place the conductive glass into the PVD deposition equipment, set the ITO target, and set the vacuum degree of the equipment to 3.0×10 -4 Pa, argon and oxygen were introduced to adjust the vacuum to 5.0×10 -1 Pa, oxygen argon percentage: 5%, coating power: 1000W, and an ITO film with a thickness of 100nm is formed on the conductive glass.

[0042] Step 3: Place the conductive glass coated with the ITO film in a vacuum annealing furnace and anneal it in a H2 atmosphere with a H2 gas flow rate of 200 sccm, an annealing temperature of 200°C, and an annealing time of 30 minutes.

[0043] Step 4: Take out the conductive glass after step 3, put it into a vacuum annealing furnace, and anneal it in a N2 atmosphere with an N2 gas flow rate of 200 sccm, an annealing temperature of 250°C, and an annealing time of 30 minutes.

[0044] Step 5: Take out the conductive glass after step 3, put it into a vacuum annealing furnace, and anneal it in an O2 atmosphere with an O2 gas flow rate of 100 sccm, an annealing temperature of 150°C, and an annealing time of 10 minutes.

[0045] Example 2

[0046] This embodiment provides a method for preparing a TCO thin film. The difference from Example 1 is that the flow rates of H2, N2, and O2 in steps 3-5 are all 120 sccm.

[0047] Example 3

[0048] This embodiment provides a method for preparing a TCO thin film. The difference from Example 1 is that the flow rates of H2, N2, and O2 in steps 3-5 are all 350 sccm.

[0049] Example 4

[0050] This embodiment provides a method for preparing a TCO thin film. The difference from Example 1 is that the annealing temperatures of H2, N2, and O2 in steps 3-5 are all 200°C.

[0051] Comparative Example 1

[0052] This comparative example provides a method for preparing a TCO thin film, comprising the steps of:

[0053] Step 1: Clean a conductive glass.

[0054] Step 2: Place the conductive glass into the PVD deposition equipment, set the ITO target, and set the vacuum degree of the equipment to 3.0×10 -4 Pa, argon and oxygen were introduced to adjust the vacuum to 5.0×10 -1 Pa, oxygen argon percentage: 5%, coating power: 1000W, and an ITO film with a thickness of 100nm is formed on the conductive glass.

[0055] Step 3: Place the conductive glass coated with the ITO film in a vacuum annealing furnace and anneal it in a H2 atmosphere with a H2 gas flow rate of 200 sccm, an annealing temperature of 200°C, and an annealing time of 30 minutes.

[0056] Comparative Example 2

[0057] This comparative example provides a method for preparing a TCO thin film, comprising the steps of:

[0058] Step 1: Clean a conductive glass.

[0059] Step 2: Place the conductive glass into the PVD deposition equipment, set the ITO target, and set the vacuum degree of the equipment to 3.0×10 -4 Pa, argon and oxygen were introduced to adjust the vacuum to 5.0×10 -1 Pa, oxygen argon percentage: 5%, coating power: 1000W, and an ITO film with a thickness of 100nm is formed on the conductive glass.

[0060] Step 3: Place the conductive glass coated with the ITO film in a vacuum annealing furnace and anneal it in a H2 atmosphere with a H2 gas flow rate of 200 sccm, an annealing temperature of 200°C, and an annealing time of 30 minutes.

[0061] Step 4: Take out the conductive glass after step 3, put it into a vacuum annealing furnace, and anneal it in an O2 atmosphere with an O2 gas flow rate of 100 sccm, an annealing temperature of 150°C, and an annealing time of 10 minutes.

[0062] Comparative Example 3

[0063] This comparative example provides a method for preparing a TCO thin film, comprising the steps of:

[0064] Step 1: Clean a conductive glass.

[0065] Step 2: Place the conductive glass into the PVD deposition equipment, set the ITO target, and set the vacuum degree of the equipment to 3.0×10 -4 Pa, argon and oxygen were introduced to adjust the vacuum to 5.0×10 -1 Pa, oxygen argon percentage: 5%, coating power: 1000W, and an ITO film with a thickness of 100nm is formed on the conductive glass.

[0066] Step 3: Take out the conductive glass after step 3, put it into a vacuum annealing furnace, and anneal it in an O2 atmosphere with an O2 gas flow rate of 100 sccm, an annealing temperature of 150°C, and an annealing time of 10 minutes.

[0067] Step 4: Take out the conductive glass after step 3, put it into a vacuum annealing furnace, and anneal it in a N2 atmosphere with an N2 gas flow rate of 200 sccm, an annealing temperature of 250°C, and an annealing time of 30 minutes.

[0068] Step 5: Place the conductive glass coated with the ITO film in a vacuum annealing furnace and anneal it in a H2 atmosphere with a H2 gas flow rate of 200 sccm, an annealing temperature of 200°C, and an annealing time of 30 minutes.

[0069] Electrical performance test: Use a four-probe tester and a Hall effect meter to test, use standard samples to calibrate and verify the equipment, and test the samples obtained in Examples 1-4 and Comparative Examples 1-3 after the test data meet the standards.

[0070] Optical performance test: Use UV-vis instrument to test, use standard sample to calibrate and verify the equipment, and after the test data reaches the standard sample qualification, test the samples obtained in Examples 1-4 and Comparative Examples 1-3.

[0071] The specific test results are shown in Table 1 below:

[0072] Table 1 Test results of the films obtained in Examples 1-4 and Comparative Examples 1-3

[0073] Group Film thickness nm Resistance Ω / sq <![CDATA[载流子浓度cm -3 ]]> Mobility cm² / (V·s) Transmittance at 550nm% Example 1 100 25.0 8.80E+20 61.885 88.545 Example 2 100 25.6 7.06E+20 59.139 88.120 Example 3 100 26.3 7.61E+20 58.225 88.326 Example 4 100 27.5 7.11E+20 56.425 88.225 Comparative Example 1 100 30.4 3.81E+20 35.094 84.150 Comparative Example 2 100 33.1 2.82E+20 26.254 86.900 Comparative Example 3 100 32.4 2.26E+20 24.034 86.336

[0074] The experimental data obtained show that the technical solution of the present invention can obtain an ITO film with relatively excellent optical and electrical properties through three-step annealing in a gas environment; by annealing the prepared ITO film in the gas atmospheres of H2, N2, and O2 in sequence, the oxygen vacancies in the film are effectively activated, the carrier concentration and mobility are increased, the contact resistance is effectively reduced, and the film performance and structural stability are improved. The order of annealing cannot be reversed, and any adjustment in the order will destroy the balance of "low resistance in the bulk phase-stable interface". If O2 is passed first, a dense In2O3 layer will be formed on the surface, blocking the diffusion of H2 to the bulk phase and the oxygen vacancies cannot be activated. If N2 is passed first, O2 / H2 cross contamination may occur. Figure 1 By performing X-ray diffraction analysis on Example 1 and Comparative Examples 1-3, the corresponding crystal plane information (hkl) can be obtained. hkl represents the Miller index, which is used to characterize the crystal plane orientation of the material, corresponding to (211), (222), etc. in the figure. Among them, the diffraction peak has a higher intensity in the (222) direction, indicating a better crystallization effect. The ITO film crystallization obtained by the embodiment of the present application has good stability.

[0075] The above embodiments are only preferred implementation modes of the present invention. It should be pointed out that for ordinary technicians in this technical field, various changes, modifications, replacements and deformations can be made to these embodiments without departing from the principles of the present invention. These technical solutions that are equivalent to the claims of the present invention all fall within the scope of protection of the present invention, and the scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a TCO thin film, characterized in that: The method comprises the following steps: depositing a TCO target material on a substrate, and annealing in H2, N2 and O2 atmospheres in sequence to obtain a TCO film.

2. The method for preparing a TCO thin film according to claim 1, wherein: The substrate includes conductive glass and a battery structure.

3. The method for preparing a TCO thin film according to claim 2, wherein: The battery structure includes a single-junction battery structure or a stacked battery structure.

4. The method for preparing a TCO thin film according to claim 1, wherein: The annealing temperature of each atmosphere is 150-300° C., and the annealing time is 5-30 minutes.

5. The method for preparing a TCO thin film according to claim 1, wherein: The gas flow rate introduced into the H2 atmosphere is 100-500 sccm.

6. The method for preparing a TCO thin film according to claim 1, wherein: The gas flow rate introduced into the N2 atmosphere is 100-500 sccm.

7. The method for preparing a TCO thin film according to claim 1, wherein: The gas flow rate introduced into the O2 atmosphere is 100-500 sccm.

8. The method for preparing a TCO thin film according to claim 1, wherein: The TCO target material includes one of ITO, IZO, AZO, GZO, SnO2, ZnO, In2O3, ICO, and IWO.

9. The method for preparing a TCO thin film according to claim 1, wherein: The TCO film has a thickness of 5 to 200 nm.

10. The method for preparing a TCO thin film according to claim 1, wherein: The TCO target material is prepared by vacuum deposition method, which includes the following steps: placing the substrate in a vacuum environment and setting the vacuum degree to 5.0×10 -4 —1.0×10 -4 Pa, argon and oxygen were introduced to adjust the vacuum to 3.0×10 -1 Pa—8.0×10 -1 Pa, oxygen-argon percentage: 0.5%-10%, control the coating power to be 600-2000W, and deposit the TCO target material onto the substrate.

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