A selenium-based compound thin film, a method for preparing the same, and an application thereof
By controlling the selenium composition of selenium-based compound films through ultra-high temperature deposition and heat treatment in a selenium-containing environment, the problem of selenium composition deviation was solved, and selenium-based compound films with high crystal quality and low defect density were achieved, thereby improving the performance of optoelectronic devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JINAN UNIVERSITY
- Filing Date
- 2022-12-30
- Publication Date
- 2026-07-24
Smart Images
Figure HDA0004029965360000011 
Figure HDA0004029965360000012
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of semiconductor optoelectronic materials and devices, and particularly relates to a selenium-based compound thin film, a preparation method thereof and an application thereof. Background Art
[0002] Selenium (Se) element has excellent optoelectronic properties, and selenium-based compound semiconductors based on the optoelectronic properties of selenium element are important optoelectronic materials. Selenium-based compound semiconductors, such as CdTe 1-x Se x (0 < x < 1), CdSe, Sb2Se3, Cu(In,Ga)Se2, Cu2Se, FeSe, FeSe2, SnSe, Cu2ZnSnSe4, etc. have excellent optoelectronic conversion properties, are widely used thin film photovoltaic materials, and have great research value and industrialization potential.
[0003] The content of selenium element in the selenium-based compound component is a key factor affecting its semiconductor properties, optoelectronic properties and defect properties. Controlling the stoichiometric ratio of selenium element in the selenium-based compound is an important means to improve the performance of compound semiconductors. In the preparation of high-quality selenium-based compound thin films, a relatively high growth temperature is usually required to ensure the crystallinity of the thin film. However, due to the low evaporation temperature and relatively small atomic mass of selenium element, the content of selenium element in the selenium-based compound component is easily affected by the growth temperature during the preparation process, resulting in selenium loss during the high-temperature process, and further leading to the problem of deviation of the selenium component in the selenium-based compound. The traditional preparation of selenium-based compound thin films mainly includes two methods: First, the one-step method for preparing selenium-based compound thin films: under the condition of avoiding large-scale deviation of selenium components, as high a growth temperature as possible is adopted; the problem of this preparation method is that the growth temperature and the corresponding crystallinity of the thin film are limited, and at the same time, the deviation of selenium components is difficult to avoid. Second, the two-step method of seleniumization after low-temperature compound deposition. This method can improve the crystallinity and selenium component control during the high-temperature seleniumization process, but the simultaneous high-temperature and Seization composite process is accompanied by complex phase problems. Therefore, realizing the controllable preparation of selenium-based compound thin films with high crystalline quality and ideal stoichiometric ratio is of great significance for obtaining high-performance selenium-based compound thin films and devices. Summary of the Invention
[0004] To address the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a method for preparing selenium-based compound thin films. This method involves obtaining a high-crystallinity selenium-based compound with a specific phase exhibiting selenium deficiency through an ultra-high temperature growth process. The selenium-based compound is then heat-treated in a selenium-containing environment to maintain the specific phase and improve the stoichiometry of selenium, resulting in a selenium-based compound with both a specific phase and a specific selenium stoichiometry. Compared to traditional methods, this method significantly improves the controllability of selenium-based compound thin film preparation, yielding selenium-based compound thin films with high crystallinity, controllable selenium composition, and low defect density, thereby enhancing the performance of optoelectronic devices based on selenium-based compound functional layers.
[0005] Another object of the present invention is to provide a selenium-based compound thin film prepared by the above preparation method.
[0006] Another object of the present invention is to provide the application of the above-mentioned selenium-based compound thin film in solar cells.
[0007] The objective of this invention is achieved through the following technical solution:
[0008] A method for preparing a selenium-based compound thin film includes the following steps:
[0009] (1) Deposition of selenium-based compounds at ultra-high temperature: Selenium-based compounds are deposited at ultra-high growth temperature to obtain specific phases and highly crystalline selenium-based compounds;
[0010] (2) Heat treatment of selenium-based compounds in a selenium-containing environment: heat treatment of selenium-based compounds at 300-600℃ in a selenium-containing environment to maintain a specific phase and improve the stoichiometry of selenium element, thereby obtaining selenium-based compounds with a specific phase and a specific stoichiometry of selenium element.
[0011] (3) This is the end, or step (2) is repeated to obtain a selenium-based compound with a specific phase and a specific stoichiometric ratio of selenium.
[0012] The ultra-high growth temperature mentioned in step (1) refers to a growth temperature higher than the temperature at which selenium is lost from the selenium-based compound. That is, at this growth temperature, selenium loss from the selenium-based compound causes a deviation in the stoichiometric ratio. At the same time, as the growth temperature increases further, the deviation in the stoichiometric ratio caused by selenium loss from the selenium-based compound intensifies.
[0013] In step (1), the degree of selenium loss is limited by a specific phase. If the loss is severe or even complete, it is usually accompanied by phase changes related to the components. Under the premise of ensuring the phase, there is a large tolerance range for different degrees of deviation of selenium components, which can be recovered through the selenization process in the subsequent step (2).
[0014] The specific phase described in step (1) generally refers to a phase with good optoelectronic response. Different selenium-based compounds have different ideal phases. The main influencing factors of the phase are the deposition temperature and composition. When the composition changes little, a specific temperature corresponds to a specific phase.
[0015] The specific selenium stoichiometry described in step (2) means that the stoichiometric proportion of selenium is 95-100%, the stoichiometric proportion of selenium vacancies is 0-5%, and the sum of the stoichiometries of selenium and selenium vacancies is 100%. The stoichiometric proportion of selenium can be controlled by the temperature and time of heat treatment in a selenium environment to avoid introducing n-type defects or even semiconductor type inversion due to excessive selenium vacancies.
[0016] Preferably, the selenium-based compound described in step (1) is a selenium-based inorganic compound, specifically Sb2Se3, CdSe, CdTe 1- x Se x (0 < x < 1), at least one of Cu(In,Ga)Se2, Cu2Se, FeSe, FeSe2, SnSe, and Cu2ZnSnSe4; more preferably Sb2Se3, CdSe, CdTe 1-x Se x (0 < x < 1) and at least one of FeSe2.
[0017] Preferably, the deposition method described in step (1) is at least one of thermal evaporation, chemical vapor deposition, physical vapor deposition, carrier gas transport deposition, close space sublimation, and magnetron sputtering.
[0018] Preferably, the deposition time described in step (1) is 30 s to 30 min; the thickness of the thin film is 0.3 to 5.0 μm.
[0019] Preferably, the ultra-high growth temperature described in step (1) is: 350-650 °C.
[0020] Preferably, the selenium-containing environment described in step (2) is a selenium-containing gaseous environment or a selenium-containing liquid environment; the selenium-containing gaseous environment is at least one of a gaseous atomic selenium environment, a gaseous molecular selenium environment, and a gaseous selenium compound environment, more preferably at least one of selenium单质 and hydrogen selenide; the selenium-containing liquid environment is a liquid selenium compound environment, more preferably selenourea.
[0021] Preferably, the heat treatment described in step (2) is a heat treatment in a selenium-containing environment. At this heat treatment temperature, selenium in the selenium environment reacts with the selenium-based compound obtained in step (1), thereby increasing the selenium content in the selenium-based compound and reducing or eliminating the deviation of the stoichiometry caused by selenium loss in the selenium-based compound.
[0022] Preferably, the heat treatment in step (2) does not change the selenium-based compound phase formed in step (1).
[0023] Preferably, the heat treatment time in step (2) is 1 to 60 minutes.
[0024] Preferably, the selenium-containing environment in step (2) is a selenium-containing gaseous environment with a pressure of 1 to 50 kPa.
[0025] The step (2) is repeated in a cycle, which means repeatedly using the same or different selenium environment, heat treatment temperature and time as in step (2) to heat treat the selenium-based compound.
[0026] A selenium-based compound thin film was prepared by the above method.
[0027] The above-mentioned application of a selenium-based compound thin film in solar cells.
[0028] A selenium-based compound solar cell has the following structure in sequence: a substrate, a buffer layer and / or an n-type electron transport layer, the aforementioned selenium-based compound thin film layer, and a metal back electrode.
[0029] The above-mentioned method for preparing a selenium-based compound solar cell includes the following steps:
[0030] (1) Deposit a buffer layer and / or an n-type electron transport layer on a transparent conductive substrate;
[0031] (2) Deposit a selenium-based compound thin film on the buffer layer and / or n-type electron transport layer according to the preparation method described above;
[0032] (3) A metal back electrode is deposited on the surface of a selenium-based compound thin film to obtain a selenium-based compound solar cell.
[0033] Preferably, the transparent conductive substrate in step (1) is FTO.
[0034] Preferably, the buffer layer in step (1) is a SnO2, ZnO, TiO2, Al2O3, MgZnO buffer layer and its composite structure; the n-type electron transport layer is an n-type CdS or CdSe electron transport layer.
[0035] Preferably, the metal back electrode in step (3) is a gold, silver, aluminum, molybdenum, or chromium metal electrode or a composite structure thereof.
[0036] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0037] Compared with traditional preparation methods, this preparation method significantly improves the controllability of selenium-based compound film preparation, resulting in selenium-based compound films with high crystallinity, controllable selenium composition, and low defect density, thereby improving the performance of optoelectronic devices based on selenium-based compound functional layers. Attached Figure Description
[0038] Figure 1 This is a device structure diagram of the antimony selenide solar cell in Example 1;
[0039] Figure 2 The JV curves are for the antimony selenide solar cells in Example 1 and Comparative Examples 1-2. Detailed Implementation
[0040] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.
[0041] Unless otherwise specified in the embodiments of this invention, the conditions shall be performed according to conventional conditions or conditions recommended by the manufacturer. All raw materials and reagents used, unless otherwise specified, are commercially available conventional products.
[0042] Example 1
[0043] This embodiment provides a selenium-based compound thin film and a method for preparing the same, the method comprising the following steps:
[0044] Step 1: Clean the substrate:
[0045] FTO conductive glass was used as the substrate and was ultrasonically cleaned in sequence with acetone, ethanol and deionized water, and then placed in an oven for drying.
[0046] Step 2: Prepare the SnO2 buffer layer:
[0047] SnO2 thin films were prepared on FTO using radio frequency magnetron sputtering. The target material was a SnO2 ceramic target with a purity of 99.99%. Before deposition, the vacuum was evacuated to 5 × 10⁻⁶ m³ / s. -3 The pressure was set below Pa, and then an argon-oxygen mixture was introduced. The working pressure was set to 0.4 Pa, the RF power supply was maintained at 90 W, and the substrate temperature was 200 °C. First, a 15-minute pre-sputtering was performed to remove impurities adsorbed on the target surface, and then the formal sputtering was performed for 5 minutes to achieve a sputtering thickness of 35 nm.
[0048] Step 3: Preparation of n-type CdS electron transport layer:
[0049] A CdS electron transport layer was prepared using a chemical bath method. First, the reaction vessel, including the beaker, reaction vessel, and graduated cylinder, was cleaned. Next, the SnO2-sputtered substrate was cleaned. After cleaning, the reaction solution was prepared. The precursors were ammonium acetate (0.7708 g), cadmium acetate (0.1333 g), and thiourea (0.1903 g). The solution volume was 500 mL, and the deposition temperature was 80 °C. The SnO2 substrate was immersed in the solution, and the deposition time was 30 minutes. The sample was removed and rinsed thoroughly with deionized water, then dried with nitrogen. The thickness was controlled between 60 and 80 nm.
[0050] Step 4: CdCl2 heat treatment of CdS thin film:
[0051] FTO / SnO2 / CdS substrates were subjected to CdCl2 heat treatment using a Czochralski device and a tube furnace. First, the substrates were immersed in a saturated cadmium chloride methanol solution and then pulled at a speed of 5 cm / min under nitrogen atmosphere to coat the CdS surface with a layer of CdCl2. Then, the substrates were placed in a tube furnace for air annealing at 400°C for 10 min.
[0052] Step 5: Prepare the Sb2Se3 absorber layer:
[0053] The Sb₂Se₃ absorber layer was prepared using a near-space sublimation method. Antimony selenide powder was used as the evaporation source. During the deposition process, the substrate temperature was set to 420℃ and the evaporation source temperature to 500℃. The deposition was completed in 3 minutes, and the film was cooled to below 100℃ before being removed. This step deposited a thin film with a thickness of 550 nm, thus obtaining the antimony selenide absorber layer.
[0054] Step 6: Heat treatment of Sb2Se3 thin film in a selenium environment:
[0055] Selenium and the sample prepared in step 5 were placed in a tube furnace. The heat treatment process was carried out in a closed, sealed chamber. Nitrogen gas was introduced to adjust the chamber pressure to 2 kPa, the heat treatment temperature was 400℃, and the time was 20 min. After the heat treatment, the surface of the film was cleaned with nitrogen gas.
[0056] Step 7: Deposit gold electrodes:
[0057] A gold electrode with a thickness of 100 nm was deposited on the Sb2Se3 absorber layer using a thermal evaporation method.
[0058] Comparative Example 1
[0059] Steps 1-4 are the same as in Example 1.
[0060] Step 5: Prepare the Sb2Se3 absorber layer:
[0061] The Sb₂Se₃ absorber layer was prepared using a near-space sublimation method. Antimony selenide powder was used as the evaporation source. During the deposition process, the substrate temperature was set to 270℃ and the evaporation source temperature to 500℃. The deposition was completed after 5 minutes, and the film was removed after cooling to below 100℃. This step deposited a thin film with a thickness of 550 nm, thus obtaining the antimony selenide absorber layer.
[0062] Step 6 is the same as step 7 in Example 1, thereby obtaining an antimony selenide thin-film solar cell.
[0063] Comparative Example 2
[0064] Steps 1-4 and 6-7 are the same as in Example 1.
[0065] Step 5: Prepare the Sb2Se3 absorber layer:
[0066] The Sb₂Se₃ absorber layer was prepared using a near-space sublimation method. Antimony selenide powder was used as the evaporation source. During the deposition process, the substrate temperature was set to 270℃ and the evaporation source temperature to 500℃. The deposition was completed after 5 minutes, and the film was removed after cooling to below 100℃. This step deposited a thin film with a thickness of 550 nm, thus obtaining the antimony selenide absorber layer.
[0067] This leads to the production of antimony selenide thin-film solar cells.
[0068] For the two antimony selenide thin-film solar cells of Example 1 and Comparative Examples 1 and 2, at AM 1.5 and 100mW / cm 2 The JV performance curve of the battery was tested using a solar simulator under sunlight, such as... Figure 2 As shown. In Example 1, the short-circuit current density of the antimony selenide thin-film solar cell obtained by heat treatment in a selenium environment was 29.6 mA cm⁻¹. -2 The open-circuit voltage was 422mV, the fill factor was 59.6%, and the photoelectric conversion efficiency was 7.44%. In contrast, the short-circuit current density of the antimony selenide thin-film solar cell (Comparative Example 1), which did not undergo heat treatment in a selenium environment, was 19.9mA / cm². -2 The open-circuit voltage was 324 mV, the fill factor was 36.4%, and the photoelectric conversion efficiency was 2.35%. The short-circuit current density of the antimony selenide thin-film solar cell without a high-temperature deposition process (Comparative Example 2) was 27.8 mA cm⁻¹. -2 The open-circuit voltage is 368mV, the fill factor is 56.6%, and the photoelectric conversion efficiency is 5.78%.
[0069] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A method for preparing a selenium-based compound thin film, characterized in that, Includes the following steps: (1) Deposition of selenium-based compounds at ultra-high temperature: Selenium-based compounds are deposited at ultra-high growth temperature to obtain specific phases and highly crystalline selenium-based compounds; (2) Heat treatment of selenium-based compounds in a selenium-containing environment: heat treatment of selenium-based compounds at 300-600 °C in a selenium-containing environment to maintain a specific phase and improve the stoichiometric ratio of selenium element, thereby obtaining selenium-based compounds with a specific phase and a specific stoichiometric ratio of selenium element; (3) This process ends here, or step (2) is repeated to obtain a selenium-based compound with a specific phase and a specific stoichiometric ratio of selenium. The ultra-high growth temperature mentioned in step (1) refers to a growth temperature higher than the selenium loss temperature in selenium-based compounds. The ultra-high growth temperature in step (1) is 420–650 °C; the deposition time in step (1) is 30 s–30 min. The selenium-based compound described in step (1) is a selenium-based inorganic compound, specifically at least one of Sb2Se3, CdSe, CdTe, Se (0 < x < 1), Cu(In,Ga)Se2, Cu2Se, FeSe, FeSe2, SnSe, and Cu2ZnSnSe4. 1-x Se x (0 < x < 1), Cu(In,Ga)Se2, Cu2Se, FeSe, FeSe2, SnSe, and Cu2ZnSnSe4.
2. The method for preparing a selenium-based compound thin film according to claim 1, characterized in that, The heat treatment time in step (2) is 1 to 60 min; the selenium-containing environment in step (2) is a selenium-containing gaseous environment with a pressure of 1 to 50 kPa.
3. The method for preparing a selenium-based compound thin film according to claim 1, characterized in that, The deposition method in step (1) is at least one of thermal evaporation, chemical vapor deposition, physical vapor deposition, carrier gas transport deposition, near-space sublimation and magnetron sputtering.
4. The method for preparing a selenium-based compound thin film according to claim 1, characterized in that, The selenium-containing environment in step (2) is a selenium-containing gaseous environment or a selenium-containing liquid environment; the selenium-containing gaseous environment is at least one of a gaseous atomic selenium environment, a gaseous molecular selenium environment, and a gaseous selenium compound environment; the selenium-containing liquid environment is a liquid selenium compound environment.
5. A selenium-based compound thin film prepared by the preparation method according to any one of claims 1 to 4.
6. The application of the selenium-based compound thin film according to claim 5 in solar cells.
7. A selenium-based compound solar cell, characterized in that, The structure consists of, in sequence: a substrate, a buffer layer and / or an n-type electron transport layer, a selenium-based compound thin film layer as described in claim 5, and a metal back electrode.
8. The method for preparing a selenium-based compound solar cell according to claim 7, characterized in that, Includes the following steps: (1) Deposit a buffer layer and / or an n-type electron transport layer on a transparent conductive substrate; (2) Depositing a selenium-based compound thin film on the buffer layer and / or n-type electron transport layer according to the preparation method of any one of claims 1 to 4; (3) A metal back electrode is deposited on the surface of a selenium-based compound thin film to obtain a selenium-based compound solar cell.