A gradient band gap antimony selenide sulfide solar cell and a preparation method thereof

Abstract

The application provides a gradient band gap selenium antimony sulfide solar cell and a preparation method thereof. The gradient band gap selenium antimony sulfide solar cell adopts a double gradient band gap selenium antimony sulfide as an absorption layer. The double gradient band gap selenium antimony sulfide absorption layer is prepared by a jet carrier gas transport vapor deposition technology, with selenium antimony sulfide particles as a source and hydrogen selenide as a selenium source. In the preparation process, the hydrogen selenide flow is adjusted from small to large and then from large to small, so that the double gradient band gap selenium antimony sulfide absorption layer is obtained. The method provided by the application is a method for depositing a selenium antimony sulfide film by using the jet carrier gas transport vapor deposition technology, and the flow of the hydrogen selenide is adjusted, so that the double gradient band gap selenium antimony sulfide absorption layer is prepared. The application provides a new preparation method of the gradient band gap selenium antimony sulfide solar cell, and the band gap structure of the selenium antimony sulfide absorption layer can be effectively optimized, which is helpful to improving the performance of the device.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic materials and solar cell fabrication, specifically a gradient bandgap antimony selenide solar cell and its fabrication method. Background Technology

[0002] Antimony-based chalcogenides, as light-absorbing layers in solar cells, possess suitable band gap widths and high absorption coefficients (10⁻⁶). 5 cm -1 With advantages such as large capacity, low price, and environmental friendliness, antimony selenide solar cells have a theoretical efficiency of up to 30%, showing great development potential. Antimony selenide, in particular, has a band gap of around 1.1 eV, and currently fabricated antimony selenide solar cells exhibit high short-circuit current density (~30 mA cm⁻¹). -2 However, the low open-circuit voltage (~500mV) of the device significantly limits further improvement in its photoelectric conversion efficiency. Antimony sulfide has a band gap of around 1.7eV, and currently fabricated antimony sulfide solar cells exhibit high open-circuit voltages (~700mV), but their short-circuit current densities are low (~20mA cm⁻¹). -2 The band gap of the absorption layer is a major factor limiting the improvement of device performance. Since both antimony selenide and antimony sulfide belong to the orthorhombic crystal system and have the same one-dimensional structure, and selenium and sulfur have similar atomic radii, the band gap of the absorption layer can be controlled by preparing antimony selenide sulfide to simultaneously obtain higher open-circuit voltage and short-circuit current density, thereby improving the photoelectric conversion efficiency of the device.

[0003] To maximize device performance, the absorption layer needs to be optimized for gradient bandgap. At the back contact interface, a wider bandgap is required to suppress recombination at the back electrode and provide a back surface field for improving the collection of photogenerated carriers. In the PN junction interface region, a suitable bandgap matching buffer layer is needed to reduce PN junction interface recombination. Simultaneously, in the effective light absorption region, a lower bandgap is required to enhance the absorption of incident light, thereby obtaining the optimal open-circuit voltage and short-circuit current density.

[0004] Currently, most conventional fabrication processes can only produce flat bandgap cells, which greatly limits the photoelectric conversion efficiency of antimony-based chalcogenide solar cells. Therefore, exploring a gradient bandgap antimony selenide sulfide solar cell and its fabrication process is of great significance for the preparation and subsequent application of high-efficiency antimony-based chalcogenide solar cells. Summary of the Invention

[0005] The purpose of this invention is to provide a gradient bandgap antimony selenide solar cell and its preparation method. A certain proportion of antimony selenide thin film is deposited by jet vapor deposition technology, and the dual gradient bandgap of the antimony selenide thin film is achieved by controlling the flow rate of the selenium source (i.e., hydrogen selenide).

[0006] The present invention is implemented as follows: a gradient bandgap antimony selenide sulfide solar cell, the structure of which, from bottom to top, consists of: a substrate, a back electrode, a dual-gradient bandgap antimony selenide sulfide absorber layer, a buffer layer, a window layer, and a top electrode; the dual-gradient bandgap antimony selenide sulfide absorber layer is prepared by jet carrier gas transport phase deposition technology, using antimony selenide particles as the source and hydrogen selenide as the selenium source. During the preparation process, the hydrogen selenide flow rate is adjusted from small to large and then from large to small to obtain the dual-gradient bandgap antimony selenide sulfide absorber layer.

[0007] In the above scheme, the substrate is glass, the back electrode is a molybdenum back electrode, the buffer layer is a cadmium sulfide buffer layer, the window layer is a zinc oxide / aluminum-doped zinc oxide layer, and the top electrode is a gold electrode.

[0008] In the above scheme, the ratio of selenium to sulfur in the antimony selenide sulfide particles is 1:1.

[0009] The above-mentioned method for preparing antimony selenide solar cells with gradient bandgap includes the following steps:

[0010] a. Clean the substrate;

[0011] b. A molybdenum back electrode is fabricated on a substrate using DC magnetron sputtering technology;

[0012] c. A dual-gradient bandgap antimony selenide sulfide absorber layer was prepared on a molybdenum back electrode using jet carrier gas transport phase deposition technology. During the preparation process, antimony selenide sulfide particles were used as the source and hydrogen selenide was used as the selenium source. Argon gas was introduced into the deposition chamber at the same time. The flow rate of hydrogen selenide was adjusted from small to large and then from large to small.

[0013] d. A cadmium sulfide buffer layer was prepared on a dual-gradient bandgap antimony selenide sulfide absorber layer using a chemical water bath method.

[0014] e. Zinc oxide and aluminum-doped zinc oxide window layers are prepared on cadmium sulfide buffer layers using radio frequency magnetron sputtering technology;

[0015] f. A gold top electrode layer is deposited on zinc oxide and aluminum-doped zinc oxide window layers using thermal evaporation technology.

[0016] Preferably, in step c, the selenium-sulfur ratio in the antimony selenide particles is 1:1.

[0017] Preferably, in step c, the evaporation temperature of the antimony selenide sulfide particles is adjusted to 520-530℃, and the time is 15-20 min.

[0018] Preferably, in step c, the hydrogen selenide flow rate is adjusted from 0 to 20-25 sccm, and then decreased to 0-5 sccm.

[0019] This invention employs jet-carrier gas transport phase-deposition technology, using antimony selenide particles with a specific selenium-to-sulfur ratio as the source, and hydrogen selenide (H₂Se) as the selenium source. The hydrogen selenide source has high reactivity and can replace sulfur elements in the vaporized antimony selenide, achieving selenium-to-sulfur substitution. Therefore, the selenium-to-sulfur ratio in the deposited antimony selenide film can be controlled by adjusting the hydrogen selenide flow rate. Due to the difference in bandgap between antimony selenide and antimony sulfide, the gradient bandgap antimony selenide film and its distribution over depth can be controlled, thereby enabling the fabrication of gradient bandgap antimony selenide films and solar cells.

[0020] Compared with existing technologies, the advantages of this invention are specifically reflected in:

[0021] 1) The bandgap structure of the prepared absorber layer can be effectively controlled. The ratio of selenium and sulfur elements and the bandgap structure of the prepared antimony selenide thin film can be controlled by adjusting the flow rate of hydrogen selenide as needed. 2) The preparation process is precise and controllable. The elemental composition of the prepared thin film can be precisely controlled by adjusting the flow rate of hydrogen selenide. Single gradient bandgap and dual gradient bandgap can be achieved. Parameters such as gradient depth and gradient thickness can be effectively designed and controlled, which is conducive to promoting the preparation and development of high-efficiency devices. 3) The gradient bandgap thin film is prepared by a one-step deposition process. The composition of the deposited antimony selenide thin film can be controlled online in real time using hydrogen selenide gas. There are no multi-step deposition processes or additional post-processing processes. The process is simple and easy to operate. 4) The vacuum process is more conducive to large-area and continuous preparation, which is beneficial to the industrialization of antimony-based chalcogenide solar cells. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the equipment used in the preparation of gradient bandgap antimony selenide sulfide thin films according to the present invention.

[0023] Figure 2 This is a schematic diagram of the source temperature curve and hydrogen selenide flow rate curve in Embodiment 1 of the present invention.

[0024] Figure 3 This is a schematic diagram of the approximate sulfur element distribution curve of the antimony selenide sulfide absorber layer prepared in Example 1 of the present invention.

[0025] Figure 4 This is a schematic diagram of the gradient bandgap antimony selenide solar cell prepared in Example 2 of the present invention. Detailed Implementation

[0026] Example 1

[0027] This invention utilizes jet vapor deposition technology to prepare gradient bandgap antimony selenide sulfide thin films, and the equipment used is as follows: Figure 1As shown. A cylinder is installed in the deposition chamber, and a cylindrical mesh screen is installed inside the cylinder. The mesh screen contains a source, which in this invention is antimony selenide sulfide particles. The mesh size of the mesh screen is smaller than the particle size of the antimony selenide sulfide particles. An elongated hole is opened on one side of the cylinder, and a first gas supply pipe is connected to the side opposite the elongated hole. The first gas supply pipe extends out of the deposition chamber and is used to introduce high-purity argon gas into the cylinder. At the same time, a second gas supply pipe is also connected to the cylinder. One end of the second gas supply pipe extends into the cylinder and is located at the elongated hole. The other end of the second gas supply pipe extends out of the deposition chamber and is used to introduce hydrogen selenide gas (as a selenium source) into the elongated hole of the cylinder. A flow meter is installed on the second gas supply pipe. One end of the mesh screen is connected to a rotating shaft. The rotating shaft passes through a bearing assembly installed on the end face of the cylinder and is connected to a drive device. The mesh screen can rotate uniformly inside the cylinder under the action of the drive device. A heater is also installed inside the cylinder to heat the source inside the mesh screen. During deposition, the elongated orifice of the cylinder faces the sample, which is placed on the heating stage. The heating stage is slidably mounted on a slide rail, and the back-and-forth movement of the heating stage allows antimony selenide sulfide in the form of vapor ejected from the elongated orifice to be uniformly deposited onto the sample.

[0028] In the specific preparation of the antimony selenide sulfide thin film, antimony selenide sulfide particles with a selenium-sulfur ratio of 1:1 (as a source, or evaporation source) are first loaded into a mesh strainer. The evaporation source temperature is set to 525℃, and the evaporation time is 18 minutes. The temperature curve is shown below. Figure 2 As shown by the solid line; the hydrogen selenide source flow rate is set and adjusted via a flow meter. The hydrogen selenide flow rate is designed to first increase and then decrease, rising uniformly from 0 to 25 sccm over the first 13 minutes, and then decreasing uniformly from 25 sccm to 5 sccm over the next 5 minutes. See the detailed flow diagram. Figure 2 As shown by the dashed line.

[0029] In the deposited antimony selenide sulfide film, the sulfur content is approximately as follows: Figure 3 As shown, the sulfur content (S / (S+Se)) decreases slowly from the back electrode to the surface, then increases again at the surface. Similarly, the band gap of the prepared antimony selenide sulfide first decreases and then increases, realizing the preparation of a dual-gradient band gap antimony selenide sulfide absorber layer.

[0030] To prepare a single-gradient bandgap antimony selenide thin film, it is only necessary to make the hydrogen selenide flux gradually increase. Therefore, the present invention can conveniently realize a single-gradient bandgap or dual-gradient bandgap antimony selenide absorber layer.

[0031] Example 2

[0032] like Figure 4As shown, the structure of the gradient bandgap antimony selenide sulfide solar cell provided by the present invention, from bottom to top, consists of: a substrate, a back electrode, an antimony selenide sulfide absorber layer, a buffer layer, a window layer, and a top electrode. The antimony selenide sulfide absorber layer is prepared using the jet vapor deposition process shown in Example 1. In this example, the substrate is glass, the back electrode is a molybdenum back electrode, the buffer layer is a cadmium sulfide buffer layer, the window layer is a zinc oxide / aluminum-doped zinc oxide layer, and the top electrode is a gold electrode.

[0033] The specific preparation steps are as follows:

[0034] (1) Cleaning the substrate

[0035] Glass amine was used as the substrate. The glass surface was rinsed sequentially with electronic cleaning agent and deionized water, and then dried with nitrogen.

[0036] (2) Preparation of molybdenum back electrode

[0037] Mo back electrode was fabricated using DC magnetron sputtering technology, with a target sputtering power density of 3.9 W / cm². 2 The sputtering pressure was 0.3 Pa, the prepared film thickness was 700 nm, and the resistivity was 3 × 10⁻⁶. -5 Ω·cm.

[0038] (3) Preparation of antimony selenide sulfide absorber layer

[0039] The absorption layer was deposited using a jet vapor deposition process, employing the method described in Example 1.

[0040] (4) Preparation of cadmium sulfide buffer layer

[0041] A cadmium sulfide buffer layer was prepared by a chemical water bath method, using cadmium sulfate as the cadmium source and thiourea as the sulfur source. The reaction temperature was set at 70℃, and the thickness of the prepared cadmium sulfide buffer layer was 80 nm.

[0042] (5) Preparation of zinc oxide and aluminum-doped zinc oxide window layer

[0043] Zinc oxide and aluminum-doped zinc oxide window layers were deposited using radio frequency magnetron sputtering technology. High-purity zinc oxide and aluminum-doped zinc oxide targets were selected for sputtering, with sputtering power densities of 0.85 W / cm², respectively. 2 1.70W / cm 2 The sputtering pressures were 0.5 Pa and 0.2 Pa, respectively, the substrate temperature was room temperature, and the thicknesses were 50 nm and 300 nm, respectively.

[0044] (6) Fabrication of gold top electrode

[0045] A gold top electrode layer was deposited using thermal evaporation technology, with high-purity gold wire as the evaporation source. The thickness of the prepared gold top electrode layer was 100 nm.

Claims

1. A gradient bandgap antimony selenide solar cell, characterized in that, Its structure, from bottom to top, consists of: a substrate, a back electrode, a dual-gradient bandgap antimony selenide sulfide absorber layer, a buffer layer, a window layer, and a top electrode. The dual-gradient bandgap antimony selenide sulfide absorber layer is prepared by jet carrier gas transport phase deposition technology, using antimony selenide particles as the source and hydrogen selenide as the selenium source. During the preparation process, the hydrogen selenide flow rate is adjusted from small to large and then from large to small to obtain the dual-gradient bandgap antimony selenide sulfide absorber layer. When preparing a dual-gradient bandgap antimony selenide sulfide absorber layer using jet-carrier gas transport phase-phase deposition technology, with antimony selenide particles as the source and hydrogen selenide as the selenium source, the equipment includes a deposition chamber containing a cylinder. Inside the deposition chamber is a cylindrical mesh screen containing antimony selenide particles, the mesh size of which is smaller than the particle size of the antimony selenide sulfide. An elongated hole is opened on one side of the cylinder, and a first gas supply pipe is connected to the side opposite the elongated hole. The first gas supply pipe extends out of the deposition chamber and is used to introduce high-purity argon gas into the cylinder. Simultaneously, a second gas supply pipe is also connected to the cylinder, one end of which extends into the cylinder and is located at the elongated hole. The other end extends out of the deposition chamber and is supplied with hydrogen selenide gas through a second gas supply pipe into the elongated hole of the cylinder. A flow meter is installed on the second gas supply pipe. One end of the mesh strainer is connected to a rotating shaft, which passes through a bearing assembly installed on the end face of the cylinder and is connected to a drive device. The mesh strainer can rotate uniformly inside the cylinder under the action of the drive device. A heater is also installed inside the cylinder to heat the antimony selenide sulfide particles inside the mesh strainer. During deposition, the elongated hole of the cylinder faces the sample, and the sample is placed on the heating stage. The heating stage is slidably mounted on a slide rail. By moving the heating stage back and forth, the antimony selenide sulfide in the form of vapor ejected from the elongated hole can be uniformly deposited on the sample.

2. The gradient bandgap antimony selenide solar cell according to claim 1, characterized in that, The substrate is glass, the back electrode is a molybdenum back electrode, the buffer layer is a cadmium sulfide buffer layer, the window layer is a zinc oxide / aluminum-doped zinc oxide layer, and the top electrode is a gold electrode.

3. The gradient bandgap antimony selenide solar cell according to claim 1, characterized in that, The selenium-sulfur ratio in the antimony selenide particles is 1:

1.

4. A method for preparing a gradient bandgap antimony selenide solar cell as described in claim 1, characterized in that, Includes the following steps: a. Clean the substrate; b. A molybdenum back electrode is fabricated on a substrate using DC magnetron sputtering technology; c. A dual-gradient bandgap antimony selenide sulfide absorber layer was prepared on a molybdenum back electrode using jet carrier gas transport phase deposition technology. During the preparation process, antimony selenide sulfide particles were used as the source and hydrogen selenide was used as the selenium source. Argon gas was introduced into the deposition chamber at the same time. The flow rate of hydrogen selenide was adjusted from small to large and then from large to small. d. A cadmium sulfide buffer layer was prepared on a dual-gradient bandgap antimony selenide sulfide absorber layer using a chemical water bath method. e. Zinc oxide and aluminum-doped zinc oxide window layers are prepared on cadmium sulfide buffer layers using radio frequency magnetron sputtering technology; f. A gold top electrode layer is deposited on zinc oxide and aluminum-doped zinc oxide window layers using thermal evaporation technology.

5. The method for preparing a gradient bandgap antimony selenide solar cell according to claim 4, characterized in that, In step c, the selenium-sulfur ratio in the antimony selenide particles is 1:

1.

6. The method for preparing a gradient bandgap antimony selenide solar cell according to claim 4, characterized in that, In step c, the evaporation temperature of the antimony selenide sulfide particles is adjusted to 520-530℃, and the time is 15-20 minutes.

7. The method for preparing a gradient bandgap antimony selenide solar cell according to claim 4, characterized in that, In step c, the hydrogen selenide flow rate is adjusted from 0 to 20-25 sccm, and then decreased to 0-5 sccm.

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