Preparation method and application of CdS / Sb2 (S, Se) 3 heterojunction

Abstract

The invention provides a preparation method and application of a CdS / Sb2 (S, Se) 3 heterojunction, and relates to the technical field of photovoltaic materials. The preparation method of the CdS / Sb2 (S, Se) 3 heterojunction comprises the following steps: depositing CdCl2 on a CdS film, and carrying out first annealing to obtain a first film; depositing a Sb2 (S, Se) 3 absorption layer on the first thin film, and performing second annealing to obtain a CdS / Sb2 (S, Se) 3 heterojunction; and the second annealing is single-face annealing, specifically, annealing is directly conducted on a platform preheated to 350-400 DEG C for 10-20 min. According to the one-way rapid heat treatment (URTP) technology for preheating, the heating speed and the cooling speed are moderate, the annealing uniformity is improved, the process time of second annealing is shortened, a proper thermal gradient is formed, uniform crystallization of the Sb2 (S, Se) 3 thin film is effectively promoted, sufficient element migration time is guaranteed, the pinhole problem caused by rapid heating can be eliminated, and the yield of the CdS / Sb2 (S, Se) 3 thin film is improved. The interface quality of the Sb2 (S, Se) 3 heterojunction is improved, and the S and / or Se loss and defect density of the Sb2 (S, Se) 3 film are reduced.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology and relates to a method for preparing a CdS / Sb2(S,Se)3 heterojunction and its application. Background Technology

[0002] Antimony sulfide selenide (Sb2(S,Se)3) materials are favored due to their suitable optical band gap (1.18-1.80 eV) and high absorption coefficient (α ≈10). 5 cm -1 With advantages such as good stability, low-temperature fabrication capability, high theoretical photoelectric conversion efficiency (>28%), and flexibility, CdS / Sb2(S,Se)3 heterojunctions have been widely studied in recent years in fields such as indoor photovoltaics, photoelectric water splitting, photodetectors, and solar cells. In CdS / Sb2(S,Se)3 heterojunctions, n-type CdS serves as the window layer, and p-type Sb2(S,Se)3 serves as the light-absorbing layer. The resulting pn heterojunction plays a crucial role in the separation and transport of photogenerated carriers. Its interface quality, bandgap matching, and crystal compatibility directly determine the photoelectric conversion efficiency (PCE) and long-term stability of the device. In the fabrication process of CdS / Sb2(S,Se)3 heterojunctions, the annealing process has a significant impact on interface quality and crystal compatibility. Insufficient annealing usually leads to poor film quality (imperfect element migration, element volatilization, poor crystal orientation, low crystallinity, and rough surface morphology) and bandgap mismatch problems.

[0003] Currently, commonly used annealing processes for CdS / Sb2(S,Se)3 heterojunctions include tube furnace annealing (OTF annealing) and hot plate annealing (HGB annealing, integrated into a glove box). HGB annealing is characterized by rapid heating and cooling, resulting in a short annealing process. However, it requires a glove box, making it unsuitable for large-scale industrial implementation. Furthermore, excessive thermal gradients during annealing significantly hinder the longitudinal crystallization uniformity and element migration of the Sb2(S,Se)3 film, increasing defect distribution. OTF annealing, on the other hand, involves slower heating and cooling, resulting in more uniform heating. However, it is difficult to establish a suitable thermal gradient, making it impossible to achieve good crystallinity in the Sb2(S,Se)3 film. Moreover, slow cooling inevitably leads to the loss of S and / or Se elements, resulting in insufficient performance of the CdS / Sb2(S,Se)3 heterojunction.

[0004] Therefore, it is necessary to optimize the preparation process of CdS / Sb2(S,Se)3 heterojunction. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing CdS / Sb2(S,Se)3 heterojunctions and their applications.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing a CdS / Sb2(S,Se)3 heterojunction, comprising the following steps: CdCl2 was deposited on a CdS film, and a first annealing was performed to obtain a first film. A Sb2(S,Se)3 absorber layer is deposited on the first thin film, and a second annealing is performed to obtain the CdS / Sb2(S,Se)3 heterojunction. The second annealing is single-sided annealing: annealing directly on a platform preheated to 350-400℃ for 10-20 minutes.

[0008] Preferably, during the second annealing, the sample to be annealed is placed in a quartz tube under an inert gas atmosphere.

[0009] More preferably, the inert gas atmosphere is purged for 2-3 minutes, and then the gas flow rate is controlled at 50±10 sccm.

[0010] More preferably, the bottom surface of the quartz tube is a plane, and the bottom surface is in contact with the heating surface of the platform.

[0011] More preferably, the quartz tube is covered with an insulation cover for heat preservation.

[0012] Preferably, the first annealing is performed at 380-400℃ for 10-15 minutes.

[0013] Preferably, the specific steps for depositing the Sb2(S,Se)3 absorber layer on the first thin film are as follows: Mix an aqueous solution of potassium antimony tartrate (0.045-0.07 g / mL), an aqueous solution of sodium thiosulfate (0.06-0.15 g / mL), and an aqueous solution of triethanolamine and stir until the mixture turns yellow. Add an aqueous solution of sodium selenosulfate (3-5 mmol / L) and stir until the mixture becomes turbid to obtain a mixed solution. The mixed solution and the first film are subjected to a hydrothermal reaction. After the reaction is completed, the mixture is rinsed with deionized water and dried to obtain the final product.

[0014] More preferably, the first film is fixed on a glass slide; The molar ratio of potassium antimony tartrate in the potassium antimony tartrate aqueous solution, sodium thiosulfate in the sodium thiosulfate aqueous solution, and sodium selenosulfate in the sodium selenosulfate aqueous solution is 1:(6-6.5):(0.015-0.02). The concentration of the triethanolamine aqueous solution is 5-8 mg / mL, and the weight of triethanolamine in the triethanolamine aqueous solution is 40-50% of the weight of potassium antimony tartrate in the potassium antimony tartrate aqueous solution.

[0015] More preferably, the mixed solution submerges the first film; The hydrothermal reaction conditions are: 120-150℃ for 1.5-4 hours.

[0016] An application of the CdS / Sb2(S,Se)3 heterojunction prepared by the preparation method described in any of the above embodiments, for use in indoor photovoltaics, photoelectric water splitting, photodetectors, or solar cells.

[0017] The beneficial effects of this invention are: (1) The present invention adopts a preheated one-way rapid thermal treatment technology (URTP), which has moderate heating and cooling rates, improves the uniformity of annealing, shortens the process time of the second annealing and forms a suitable thermal gradient, effectively promotes the uniform crystallization of Sb2(S,Se)3 film and ensures sufficient element migration time, which helps to eliminate the pinhole problem caused by rapid heating, improves the interface quality of CdS / Sb2(S,Se)3 heterojunction, reduces the loss of S and / or Se and the defect density of Sb2(S,Se)3 film.

[0018] (2) The second annealing method in this invention is simple, requires low equipment, is easy to operate, and is suitable for industrial implementation. It can significantly reduce the manufacturing cost of CdS / Sb2(S,Se)3 heterojunction and promote its industrialization. Attached Figure Description

[0019] Figure 1 The image shows the surface and cross-section of the CdS / Sb2(S,Se)3 heterojunction obtained in Example 1.

[0020] Figure 2 SEM images of the surface and cross-section of the CdS / Sb2(S,Se)3 heterojunction obtained in Comparative Example 1.

[0021] Figure 3 SEM images of the surface and cross-section of the CdS / Sb2(S,Se)3 heterojunction obtained in Comparative Example 2.

[0022] Figure 4 This is a comparison of the XRD results of the CdS / Sb2(S,Se)3 heterojunctions obtained in Example 1, Comparative Example 1, and Comparative Example 2.

[0023] Figure 5 A comparison of the voltage-current density relationships of CdS / Sb2(S,Se)3 heterojunction assembled solar cells obtained in Example 1, Comparative Example 1, and Comparative Example 2.

[0024] Figure 6 Comparison of EQE performance of CdS / Sb2(S,Se)3 heterojunction assembled solar cells obtained in Example 1, Comparative Example 1, and Comparative Example 2. Detailed Implementation

[0025] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0026] On one hand, this invention proposes a method for preparing a CdS / Sb2(S,Se)3 heterojunction, the steps of which include: CdCl2 was deposited on a CdS film, and a first annealing was performed to obtain a first film. A Sb2(S,Se)3 absorber layer is deposited on the first thin film, and a second annealing is performed to obtain a CdS / Sb2(S,Se)3 heterojunction. The second annealing is single-sided annealing: anneal directly on a platform preheated to 350-400℃ for 10-20 minutes.

[0027] In this invention, after depositing an Sb2(S,Se)3 absorber layer on the surface of the first thin film, the second annealing is performed directly on a preheated platform. This results in rapid heat transfer, high uniformity, and a good annealing effect. Furthermore, single-sided annealing can create a suitable thermal gradient, thereby improving the interface quality of the CdS / Sb2(S,Se)3 heterojunction. Since the heating process is omitted, the heating time for the second annealing is short, reducing the loss of S and / or Se, and also reducing the defect density of the Sb2(S,Se)3 thin film. Therefore, the second annealing process of this invention can improve the performance of the CdS / Sb2(S,Se)3 heterojunction. For example, the conditions for the second annealing could be annealing at 350℃ for 10 min, 350℃ for 15 min, 350℃ for 20 min, 360℃ for 10 min, 360℃ for 15 min, 360℃ for 20 min, 380℃ for 10 min, 380℃ for 15 min, 380℃ for 20 min, 400℃ for 10 min, 400℃ for 15 min, or 400℃ for 20 min. Furthermore, during the second annealing, the preheating temperature of the platform is 360-380℃, and the annealing time is 10-15 min.

[0028] In some embodiments, during the second annealing, the sample to be annealed is placed in a quartz tube under an inert gas atmosphere. After depositing an Sb₂(S,Se)₃ absorber layer on the first thin film, a deposition structure (the sample to be annealed) is formed. The inert gas atmosphere helps prevent the CdS / Sb₂(S,Se)₃ heterojunction from being oxidized. There are no particular limitations on the inert gas atmosphere; it can be argon and / or helium.

[0029] In some embodiments, the inert gas atmosphere is maintained by purging for 2-3 minutes, followed by controlling the gas flow rate to 50 ± 10 sccm. This technical solution can continuously maintain the inert gas atmosphere during the second annealing process.

[0030] In some embodiments, the bottom surface of the quartz tube is flat and fits into the heating surface of the platform. The flat bottom surface of the quartz tube allows for good fit with the heating platform, enabling heat to be conducted more quickly and evenly from the preheating platform into the quartz tube and to perform a second annealing on the deposited structure, thereby obtaining a CdS / Sb2(S,Se)3 heterojunction.

[0031] In some embodiments, the quartz tube is covered and insulated with a heat-insulating cover. Covering the quartz tube with a heat-insulating cover prevents heat loss from the heating platform, allowing more and faster heat to be conducted into the quartz tube. Furthermore, the heat-insulating cover can also cover the heating platform, forming a complete enclosure of both the heating platform and the quartz tube.

[0032] In some embodiments, the first annealing is annealing at 380-400°C for 10-15 minutes. For example, the first annealing can be annealing at 380°C for 10 minutes, 380°C for 12 minutes, 380°C for 15 minutes, 400°C for 10 minutes, 400°C for 11 minutes, 400°C for 15 minutes, etc.

[0033] There are no particular restrictions on the preparation method of CdS thin films. For example, one method is to put 32 mL of 15 mmol / L CdSO4 solution, 16 mL of 1.5 mol / L thiourea solution, 40 mL of ammonia water and 220 mL of deionized water into a beaker, preheat it in a 66°C water bath for 2 min, then add 16 mL of thiourea and place it in a clean FTO glass. After deposition in a 66°C water bath for 22 min, remove it, rinse and dry it to obtain a CdS thin film, which is then loaded onto an FTO glass.

[0034] For example, one method for depositing CdCl2 on a CdS film is to prepare a CdCl2 methanol solution with a concentration of 15 mg / mL, and then spin-coat it onto the deposited CdS film using a spin coater.

[0035] In some embodiments, the specific steps for depositing a Sb2(S,Se)3 absorber layer on the first thin film are as follows: Mix an aqueous solution of potassium antimony tartrate (0.045-0.07 g / mL), an aqueous solution of sodium thiosulfate (0.06-0.15 g / mL), and an aqueous solution of triethanolamine and stir until the mixture turns yellow. Add an aqueous solution of sodium selenosulfate (3-5 mmol / L) and stir until the mixture becomes turbid to obtain a mixed solution. The mixed solution and the first film were subjected to a hydrothermal reaction. After the reaction was completed, the film was rinsed with deionized water and dried to obtain the final product.

[0036] For potassium antimony tartrate aqueous solution, potassium antimony tartrate trihydrate can be used for preparation, for example, 0.6679g of potassium antimony tartrate trihydrate dissolved in 10mL of deionized water; for sodium thiosulfate aqueous solution, sodium thiosulfate pentahydrate can be used for preparation, for example, 1.5884g of sodium thiosulfate pentahydrate dissolved in 10mL of deionized water.

[0037] In some embodiments, the first film is fixed on a glass slide, and there are no particular restrictions on the fixing method. For example, high-temperature resistant double-sided adhesive can be used to fix the first film on the glass slide. The molar ratio of potassium antimony tartrate in aqueous solution, sodium thiosulfate in aqueous solution, and sodium selenosulfate in aqueous solution is 1:(6-6.5):(0.015-0.02). Different molar ratios of potassium antimony tartrate, sodium thiosulfate, and sodium selenosulfate result in different properties of the obtained CdS / Sb2(S,Se)3 heterojunction, including differences in band gap, open-circuit voltage, and short-circuit current. For example, the molar ratio of potassium antimony tartrate, sodium thiosulfate, and sodium selenosulfate can be 1:6:0.015, 1:6:0.018, 1:6:0.02, 1:6.2:0.015, 1:6.2:0.018, 1:6.2:0.02, 1:6.3:0.015, 1:6.3:0.018, 1:6.3:0.02, 1:6.5:0.015, 1:6.5:0.018, 1:6.5:0.02, etc.

[0038] The concentration of the triethanolamine aqueous solution is 5-8 mg / mL, and the weight of triethanolamine in the triethanolamine aqueous solution is 40-50% of the weight of potassium antimony tartrate in the potassium antimony tartrate aqueous solution. For example, the concentration of the triethanolamine aqueous solution can be 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, etc. In some embodiments, the mixed solution floods the first film, which can ensure that the surface of the first film forms an Sb2(S,Se)3 absorption layer as completely as possible; The conditions for hydrothermal reaction are: 120-150℃ for 1.5-4 hours. For example, the conditions for hydrothermal reaction can be 120℃ for 4 hours, 130℃ for 3 hours, 140℃ for 2.5 hours, 150℃ for 1.5 hours, etc.

[0039] On the other hand, the present invention also proposes an application of the CdS / Sb2(S,Se)3 heterojunction prepared by the preparation method described in any of the above embodiments, for use in indoor photovoltaics, photoelectric water splitting, photodetectors or solar cells.

[0040] The technical solution of the present invention will be further described and illustrated below with reference to various embodiments. Unless otherwise specified, the parts mentioned in the following embodiments are parts by weight.

[0041] Example 1 CdS thin film deposition: 32 mL of 15 mmol / L CdSO4 solution, 16 mL of 1.5 mol / L thiourea solution, 40 mL of ammonia water, and 220 mL of deionized water were placed in a beaker and preheated in a 66°C water bath for 2 min. Then, 16 mL of thiourea was added, and a clean FTO glass was placed inside. After deposition in the 66°C water bath for 22 min, the film was removed, rinsed, and dried.

[0042] CdCl2 treatment: A CdCl2 methanol solution with a concentration of 15 mg / mL was prepared and then spin-coated onto the deposited CdS film using a spin coater. The treated CdS film was then placed on a hot stage at 400 °C for air annealing for 11 min and rapidly cooled to room temperature to obtain the first film.

[0043] Preparation of the Sb2(S,Se)3 absorber layer: 0.6679 g (1 mmol) potassium antimony tartrate trihydrate, 1.5884 g (6.4 mmol) sodium thiosulfate pentahydrate, and 120 mg triethanolamine were dissolved in 10 mL, 10 mL, and 20 mL of deionized water, respectively, to obtain the first, second, and third solutions. The first, second, and third solutions were mixed and stirred on a magnetic stirrer until the solution turned yellow. Then, 5 mL of a 4 mmol / L (0.02 mmol) sodium selenosulfate aqueous solution was added, and the mixture was stirred until the solution became turbid, obtaining a mixed solution. One side of the first film was attached to a glass slide with high-temperature double-sided adhesive tape, and a polytetrafluoroethylene (PTFE) liner was placed inside. The mixed solution was then added and submerged. The PTFE liner was placed in a hydrothermal reactor and reacted in an oven at 130°C for 3 hours. After the reaction, the sample was cooled, rinsed with deionized water, dried, and then subjected to the following second annealing process: The sample was placed in a sealed, irregularly shaped quartz tube with a flat bottom. The tube was purged with inert Ar gas for 2.5 min, followed by a gas flow rate of 50 sccm. The tube was then placed on a preheated platform at 360°C, with the bottom of the tube in contact with the platform surface. A heat-insulating cover was placed on top, and the sample was annealed at 360°C for 10 min. After annealing, the tube was removed and allowed to cool to room temperature. The resulting CdS / Sb₂(S,Se)₃ heterojunction, with a structure of FTO / CdS / Sb₂(S,Se)₃, was obtained.

[0044] Example 2 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the time for the second annealing is adjusted from 10 minutes to 15 minutes. The remaining steps remain unchanged.

[0045] Example 3 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the annealing temperature during the second annealing was adjusted from 360°C to 380°C. The remaining steps remain unchanged.

[0046] Comparative Example 1 The difference between this comparative example and Example 1 is that in Example 1, the second annealing was performed using the HGB method (in a glove box under an Ar atmosphere), with a heating rate of 10°C / min, and annealing at 360°C for 10 min. The remaining steps remained unchanged.

[0047] Comparative Example 2 The difference between this comparative example and Example 1 is as follows: In Example 1, the second annealing was performed using the OTF method (in a tube furnace, the gas was purged with inert Ar gas for 2.5 min, and the gas flow rate was controlled at 50 sccm during the heating process), with a heating rate of 10℃ / min, and annealing was carried out at 360℃ for 10 min. The remaining steps remained unchanged.

[0048] The surface and cross-sectional SEM images of the CdS / Sb2(S,Se)3 heterojunctions obtained in Example 1, Comparative Example 1, and Comparative Example 2 are attached as follows. Figure 1 Appendix Figure 2 and attached Figure 3 As shown, the morphology exhibits significant differences. The annealing method of URTP of the present invention (Example 1) can promote bidirectional crystallization of Sb2(S,Se)3 thin films, thereby forming smaller and well-crystallized clusters in the film. This is beneficial for improving the collection of hole carriers in subsequent devices, and the surface morphology of the film is smooth, with almost no pinholes observed in the cross-sectional morphology. The rapid heating and cooling process of the method in Comparative Example 1 (HGB) resulted in obvious pinholes in the bulk phase of the Sb2(S,Se)3 thin film and even at the CdS / Sb2(S,Se)3 interface. In addition, due to the excessive thermal gradient of the HGB method leading to non-uniform crystallization, some large clusters can also be observed on the surface of its film. The method in Comparative Example 2 (OTF) has smaller surface clusters, and only a few small pinholes are observed in the Sb2(S,Se)3 thin film.

[0049] The lattice orientation of quasi-one-dimensional Sb₂(S,Se)₃ thin films plays a crucial role in their photoelectric properties. X-ray diffraction (XRD) characterization (grazing incidence angle 0.5°) was performed on Sb₂(S,Se)₃ thin films prepared under different second annealing techniques, as shown in the attached figure. Figure 4 As shown, URTP represents Example 1, HGB represents Comparative Example 1, and OTF represents Comparative Example 2. From... Figure 4 In (a), obvious differences in diffraction peaks can be observed. These diffraction peaks are attributed to the (211) and (221) crystal planes of Sb2(S,Se)3 films annealed by different methods. Figure 4(b) and 4(c)). It can be seen that the XRD diffraction curves of the three samples all show peak overlap, indicating that the crystallization of the back surface of the Sb2(S,Se)3 film is poor. Figure 4 (b) and Figure 4 The peak fitting results in (c) show that the (211) diffraction peak of the HGB film has the largest full width at half maximum (FWHM), indicating that its back interface has the worst crystallinity. Furthermore, the (221) diffraction peak of the HGB film exhibits a large angular shift relative to the URTP and OTF films, suggesting that the excessive thermal gradient of the HGB annealing technique leads to longitudinal non-uniform crystallization of the Sb2(S,Se)3 film. In contrast, the (221) diffraction peaks of the URTP and OTF films have smaller FWHM values, indicating that uniform heating is more conducive to uniform crystallization. Figure 4 As shown in (d), the selected main ( HK 1) and ( HK 0) The texture factor (TC) of the crystal plane indicates that the HGB thin film ( HK 0) The TC value of the crystal plane is higher than that of other thin films, indicating that its carrier transport performance is the worst. Therefore, large-sized clusters suffer greater heat loss and thermal gradient during crystallization, resulting in poorer crystallinity. URTP and OTF methods can effectively limit excessive heat loss and thermal gradient, thereby obtaining better crystallinity, superior vertical orientation, and carrier transport performance.

[0050] The CdS / Sb2(S,Se)3 heterojunctions of Examples 1-3 and Comparative Examples 1-2 were assembled into solar cells according to the device structure FTO / CdS / Sb2(S,Se)3 / Spiro-OMeTAD / Au. The performance of the solar cells is shown in Table 1 below.

[0051] The voltage-current density relationships for Example 1 (TFSC-URTP), Comparative Example 1 (TFSC-HGB), and Comparative Example 2 (TFSC-OTF) are shown in the appendix. Figure 5 As shown in the figure, the EQE (external quantum efficiency) performance of solar cells in the 650~1100nm range is compared. Figure 6 As shown.

[0052] Table 1

[0053] From Table 1 and Appendix Figure 5 It can be seen that FTSC-HGB devices have the lowest V OC and the highest J SCThis is because rapid heating leads to pinhole problems and poor crystallinity at the back interface (especially the formation of clusters), which exacerbates heat loss and thermal gradient, resulting in undesirable carrier recombination loss. However, the unidirectional uniform heating process of the HGB method promotes the formation of high-quality CdS / Sb2(S,Se)3 heterojunctions.

[0054] Appendix Figure 6 In the results, the integral JSC extracted from the EQE data agrees well with the JV results. Clearly, the defects and bandgap tail states in the TFSC-OTF device are more severe than those in the TFSC-HGB and TFSC-URTP devices, indicating the loss of S and / or Se elements in the OTF film. This suggests that more N-type VS / Se defects may form in the TFSC-OTF device than in the TFSC-URTP and FSC-HGB devices. Therefore, the URTP annealing method of this invention is more suitable for preparing high-quality Sb2(S,Se)3 thin films and devices. Thus, the novel URTP annealing technology proposed in this invention can effectively improve the vertical growth orientation and back-interface crystallinity of the Sb2(S,Se)3 thin film, thereby improving the heterojunction quality and reducing the overall carrier transport barrier of the device. This significantly improves the open-circuit voltage and fill factor of the Sb2(S,Se)3 solar cell, achieving a photoelectric conversion efficiency exceeding 10%.

[0055] Therefore, this invention proposes a novel unidirectional rapid thermal treatment (URTP) method, characterized by a small thermal gradient, moderate heating / cooling rates, and simplified equipment, possessing the following five key advantages: 1) The uniform heating process with a small thermal gradient effectively promotes the uniform crystallization of Sb2(S,Se)3 films; 2) Ensuring sufficient element migration time helps eliminate pinhole problems caused by rapid heating; 3) URTP effectively enhances the separation, transport, and extraction efficiency of charge carriers at the CdS / Sb2(S,Se)3 interface; 4) The URTP method effectively suppresses the loss of S / Se elements during annealing, thereby reducing defect density and extending charge carrier lifetime; 5) The simplified equipment frees the Sb2(S,Se)3 film crystallization process from dependence on glove boxes and traditional tube furnaces, greatly improving the convenience of annealing and reducing process costs; it has better results than existing HGB annealing and OTF annealing methods.

[0056] As described above, the basic principles, main features, and advantages of the present invention have been shown and described. Those skilled in the art should understand that the present invention is not limited to the above embodiments, which are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent changes and modifications made in accordance with the scope of the patent and the description should still fall within the scope of the present invention. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a CdS / Sb2(S,Se)3 heterojunction, characterized in that the step... include: CdCl2 was deposited on a CdS film, and a first annealing was performed to obtain a first film. A Sb2(S,Se)3 absorber layer is deposited on the first thin film, and a second annealing is performed to obtain the CdS / Sb2(S,Se)3 heterojunction. The second annealing is single-sided annealing: annealing directly on a platform preheated to 350-400℃ for 10-20 minutes.

2. The preparation method according to claim 1, characterized in that, During the second annealing, the sample to be annealed is placed in a quartz tube under an inert gas atmosphere.

3. The preparation method according to claim 2, characterized in that, The inert gas atmosphere is purged for 2-3 minutes, and then the gas flow rate is controlled at 50±10 sccm.

4. The preparation method according to claim 2, characterized in that, The bottom surface of the quartz tube is flat and is in contact with the heating surface of the platform.

5. The preparation method according to claim 2, characterized in that, The quartz tube is covered with an insulation cover for heat preservation.

6. The preparation method according to claim 1, characterized in that, The first annealing is performed at 380-400℃ for 10-15 minutes.

7. The preparation method according to claim 1, characterized in that, The specific steps for depositing the Sb2(S,Se)3 absorber layer on the first thin film are as follows: Mix an aqueous solution of potassium antimony tartrate (0.045-0.07 g / mL), an aqueous solution of sodium thiosulfate (0.06-0.15 g / mL), and an aqueous solution of triethanolamine and stir until the mixture turns yellow. Add an aqueous solution of sodium selenosulfate (3-5 mmol / L) and stir until the mixture becomes turbid to obtain a mixed solution. The mixed solution and the first film are subjected to a hydrothermal reaction. After the reaction is completed, the mixture is rinsed with deionized water and dried to obtain the final product.

8. The preparation method according to claim 7, characterized in that, The first film is fixed on the glass slide; The molar ratio of potassium antimony tartrate in the potassium antimony tartrate aqueous solution, sodium thiosulfate in the sodium thiosulfate aqueous solution, and sodium selenosulfate in the sodium selenosulfate aqueous solution is 1:(6-6.5):(0.015-0.02). The concentration of the triethanolamine aqueous solution is 5-8 mg / mL, and the weight of triethanolamine in the triethanolamine aqueous solution is 40-50% of the weight of potassium antimony tartrate in the potassium antimony tartrate aqueous solution.

9. The preparation method according to claim 7, characterized in that, The mixed solution submerges the first film; The conditions for the hydrothermal reaction are: 120-150℃ for 1.5-4 hours.

10. The application of a CdS / Sb2(S,Se)3 heterojunction prepared by the preparation method according to any one of claims 1-9, characterized in that, Used in indoor photovoltaics, photocatalytic water splitting, photodetectors, or solar cells.

Images