Antimony selenide flexible thin film photodetector, preparation method and application thereof, and blood oxygen detection device

Abstract

The application discloses a flexible antimony selenide thin film photodetector and a preparation method and application thereof and a blood oxygen detection device, and relates to the technical field of photodetectors. The preparation method of the photodetector comprises the following steps: taking Mo as a target material, magnetron sputtering Mo on a flexible substrate under the conditions that the pressure is 1.5-2.0 Pa and the power is 100-120 W for 22-25 min to form a first Mo thin film layer; magnetron sputtering Mo on the first Mo thin film layer under the conditions that the pressure is 0.3-0.5 Pa and the power is 230-250 W for 15-18 min to form a second Mo thin film layer; sequentially forming an Sb2Se3 flexible thin film layer, a buffer layer and a window layer on the second Mo thin film layer, and forming a top electrode on the window layer and the second Mo thin film layer to obtain the antimony selenide flexible thin film photodetector, wherein the responsivity of the photodetector reaches 0.5 A / W, the detectivity reaches 10 12 Jones, blood oxygen detection can be realized, and the accuracy is high.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric detectors, and in particular to an antimony selenide flexible thin film photoelectric detector, a preparation method and application thereof, and a blood oxygen detection device. Background Art

[0002] Semiconductor photodetectors are photon-to-electron conversion devices that utilize semiconductors' absorption of light to generate specialized effects such as photoconductivity, photovoltaics, and photothermoelectrics. Photodetectors play a vital role in healthcare, and blood oxygen saturation is a crucial data point in biomedical testing. Accurately and in real time, using photodetectors for nondestructive testing has become a research hotspot, yet presents significant challenges. Currently, most commercially available photodetectors are based on silicon. Silicon offers advantages such as abundant availability and mature fabrication processes, but its indirect bandgap significantly limits its efficient absorption and utilization of incident light. Furthermore, traditional silicon-based photodetectors often utilize a three-dimensional bulk channel structure, which compromises device transparency and flexibility. Imperfect skin contact can also introduce external noise, leading to significant measurement errors in the characteristic signal, hindering their application in flexible, wearable human blood oxygen saturation monitoring. Therefore, the development of high-performance flexible photodetectors with high responsivity / detectability, ultrafast response speed, and robust noise immunity holds significant scientific and industrial application value.

[0003] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0004] Based on the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide an antimony selenide flexible thin film photoelectric detector, a preparation method and application thereof, and a blood oxygen detection device, aiming to provide a flexible photoelectric detector with high responsiveness, high detectability and fast response speed that can be used for blood oxygen detection.

[0005] The technical solutions of the present invention are as follows:

[0006] A first aspect of the present invention provides a method for preparing an antimony selenide flexible thin film photodetector, wherein the method for preparing the antimony selenide flexible thin film photodetector comprises the following steps:

[0007] providing a flexible substrate;

[0008] Using Mo as a target, magnetron sputtering is performed on the flexible substrate for 22 to 25 minutes at a pressure of 1.5 to 2.0 Pa and a power of 100 to 120 W to form a first Mo thin film layer;

[0009] Using Mo as a target, magnetron sputtering is performed on the first Mo thin film layer for 15 to 18 minutes at a pressure of 0.3 to 0.5 Pa and a power of 230 to 250 W to form a second Mo thin film layer;

[0010] forming a Sb2Se3 flexible thin film layer on the second Mo thin film layer;

[0011] forming a buffer layer on the Sb2Se3 flexible thin film layer;

[0012] forming a window layer on the buffer layer;

[0013] A top electrode is formed on the window layer and the second Mo thin film layer to obtain the antimony selenide flexible thin film photodetector.

[0014] Optionally, forming a buffer layer on the Sb2Se3 flexible thin film layer by chemical water bath deposition;

[0015] The buffer layer includes at least one of a CdS buffer layer, a ZnO buffer layer, and a SnO2 buffer layer.

[0016] Optionally, forming a window layer on the buffer layer by magnetron sputtering;

[0017] The window layer includes at least one of an indium tin oxide window layer, a fluorine-doped tin oxide window layer, and an aluminum-doped zinc oxide window layer.

[0018] Optionally, forming a top electrode on the window layer and the second Mo thin film layer by thermal evaporation;

[0019] The top electrode includes at least one of an Ag top electrode, an Al top electrode, and a Ni top electrode.

[0020] Optionally, the flexible substrate is one of a polyimide flexible substrate, a polyethylene terephthalate flexible substrate, a polycarbonate flexible substrate and a polyethylene naphthalate flexible substrate.

[0021] Optionally, the step of forming a Sb2Se3 flexible thin film layer on the second Mo thin film layer specifically includes: using Sb as a target material, magnetron sputtering on the second Mo thin film layer for 15 to 17 minutes under the conditions of a pressure of 1.0 to 1.2 Pa and a power of 30 to 35 W to form an Sb precursor thin film;

[0022] The Sb precursor film is selenized in an inert gas atmosphere at a temperature of 400-420° C. to form a Sb 2 Se 3 flexible film layer on the second Mo film layer.

[0023] A second aspect of the present invention provides an antimony selenide flexible thin film photodetector, wherein the antimony selenide flexible thin film photodetector is prepared by the preparation method of the antimony selenide flexible thin film photodetector described above.

[0024] A third aspect of the present invention provides the use of the antimony selenide flexible thin film photodetector described above in blood oxygen detection for purposes other than disease diagnosis.

[0025] A fourth aspect of the present invention provides a blood oxygen detection device, wherein the blood oxygen detection device includes the antimony selenide flexible thin film photodetector of the present invention as described above.

[0026] Optionally, the blood oxygen detection device also includes a signal acquisition and processing device and a light source. The signal acquisition and processing device is electrically connected to the antimony selenide flexible thin film photodetector. The light source is arranged opposite to the antimony selenide flexible thin film photodetector, and the light source emits visible light with a wavelength of 635nm and near-infrared light with a wavelength of 905nm.

[0027] Beneficial effect: The antimony selenide flexible thin film photodetector prepared by the method provided by the present invention can realize self-driven operation without external bias, with a response of 0.5A / W and a detection accuracy of 10 12 Jones, for the first time, achieved nanosecond response speeds, with response times as low as 73ns and recovery times as low as 317ns. Furthermore, the flexible thin-film photodetector can accurately measure blood oxygen levels, with an error within 3% compared to the display of a commercial oximeter. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the structure of the antimony selenide flexible thin film photodetector in Example 1.

[0029] Figure 2 This is a graph showing the response speed of the antimony selenide flexible thin film photodetector in Example 1.

[0030] Figure 3 Schematic diagram of blood oxygen detection using the antimony selenide flexible thin film photodetector in Example 1.

[0031] Figure 4 This is a graph showing the blood oxygen saturation detection results of the antimony selenide flexible thin film photodetector, commercial Si photodetector, and commercial oximeter in Example 1. DETAILED DESCRIPTION

[0032] The present invention provides an antimony selenide flexible thin-film photodetector, its preparation method and application, and a blood oxygen detection device. To clarify the objectives, technical solutions, and effects of the present invention, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0033] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0034] Through research, the inventors discovered that further improving the performance of antimony selenide flexible thin-film photodetectors requires addressing the following issues: the controllable preparation of highly ductile flexible films; how to reduce carrier recombination at the surface / interface of flexible devices; and the coordinated regulation of functional layers to improve the separation and transmission efficiency of photogenerated carriers while ensuring the generation of photogenerated carriers, thereby achieving an overall improvement in device responsivity, detection, and response speed. Therefore, an embodiment of the present invention provides a method for preparing an antimony selenide flexible thin-film photodetector, comprising the following steps:

[0035] S1. providing a flexible substrate;

[0036] S2. Using Mo as a target, magnetron sputtering is performed on the flexible substrate for 22 to 25 minutes at a pressure of 1.5 to 2.0 Pa and a power of 100 to 120 W to form a first Mo thin film layer;

[0037] S3, using Mo as a target, magnetron sputtering on the first Mo thin film layer for 15 to 18 minutes at a pressure of 0.3 to 0.5 Pa and a power of 230 to 250 W to form a second Mo thin film layer;

[0038] S4, forming a Sb2Se3 flexible thin film layer on the second Mo thin film layer;

[0039] S5, forming a buffer layer on the Sb2Se3 flexible thin film layer;

[0040] S6, forming a window layer on the buffer layer;

[0041] S7. Form a top electrode on the window layer and the second Mo thin film layer to obtain the antimony selenide flexible thin film photodetector.

[0042] In the present invention, the purpose of preparing two Mo thin film layers at different pressures, powers and times is to optimize the adhesion and conductivity of the film. First, magnetron sputtering deposition is performed at a higher pressure and lower power to form a first Mo thin film layer that is denser and has stronger adhesion to the flexible substrate. Then, magnetron sputtering deposition is performed at a lower pressure and higher power to obtain a second Mo thin film layer with good crystallinity and strong conductivity, thereby optimizing the performance of the overall back contact layer (the first Mo thin film layer and the second Mo thin film layer as a whole constitute the back contact layer). The combination of the two Mo thin films not only ensures good adhesion of the film, but also improves its electrical properties, which is beneficial to improving the separation and transmission efficiency of the generated carriers, and achieving an overall improvement in the device's responsiveness, detection and response speed.

[0043] In addition, the use of antimony selenide (Sb2Se3) in the present invention to prepare photodetectors has the following advantages: ① Structural advantage: The unique one-dimensional structure of Sb2Se3 enables it to achieve grain boundary free dangling bonds when arranged along the band direction, thus being intrinsically benign, which is beneficial to reducing carrier recombination losses; at the same time, the carriers along the one-dimensional [Sb4Sb6] n The chain is effectively transported, which is conducive to eliminating the lateral crosstalk between detector pixels and is expected to achieve ultra-fast response speed. In addition, the one-dimensional structure has a high deformation tolerance. The fracture strain of Sb2Se3 is as high as 28%, which is much larger than that of three-dimensional Si (17%). It is highly consistent with the anti-bending deformation requirements of flexible wearable photodetectors, and can fit perfectly with the skin, reducing external noise interference, thereby achieving more accurate measurements. ② Preparation advantages, Sb2Se3 is a binary single-phase compound, which is easy to prepare and has a low crystallization temperature (133°C). The corresponding detector is highly compatible with CMOS technology, which can provide greater tolerance for the selection of flexible substrates. ③ Performance advantages, the direct band gap width of Sb2Se3 is about 1.2eV, and the absorption coefficient in the visible light region is greater than 10 5 cm -1 , which can effectively cut the thickness and shorten the distance of carrier migration / diffusion; the electron and hole mobilities of Sb2Se3 are 15cm 2 ·V -1 ·s -1 and 42cm 2 ·V -1 ·s -1 The carrier recombination lifetime reaches 70ns, and the relative dielectric constant is as high as 15, which can effectively weaken the capture of free electrons or holes.

[0044] The antimony selenide flexible thin film photodetector provided by the present invention can realize self-driven operation without external bias, with a response of 0.5A / W and a detection accuracy of 10 12Jones, the response speed reaches the ns level for the first time, with the response time as low as 73ns and the recovery time as low as 317ns. In addition, the flexible thin film photodetector can fit the skin perfectly to avoid introducing external noise interference. In addition, the antimony selenide flexible thin film photodetector can realize flexible wearable blood oxygen detection, specifically through the finger position transmission mode of 635nm visible light and 905nm near-infrared light dual laser beams to obtain photoplethysmography (PPG) signals, to realize human blood oxygen detection with high accuracy, and the error is within 3% compared with the display results of commercial oximeters.

[0045] In step S1, in some embodiments, the flexible substrate is one of a polyimide (PI) flexible substrate, a molybdenum foil flexible substrate, a stainless steel foil flexible substrate, and a mica sheet flexible substrate, but is not limited thereto.

[0046] Among them, the PI flexible substrate is highly consistent with the anti-bending deformation requirements of the Sb2Se3 flexible thin film layer, and a high-quality Sb2Se3 flexible thin film layer with dense micron-level grain stacking, [hk1] benign grain boundaries, high carrier mobility, preferentially oriented growth and full depletion can be prepared on it.

[0047] In step S2, as an example, the pressure used when forming the first Mo thin film layer can be 1.5 Pa, 1.6 Pa, 1.7 Pa, 1.8 Pa, 1.9 Pa or 2.0 Pa, etc., the power used can be 100 W, 105 W, 110 W, 115 W or 120 W, etc., and the magnetron sputtering time can be 22 min, 23 min, 24 min or 25 min, etc.

[0048] In step S3, as an example, the pressure used when forming the second Mo thin film layer can be 0.3 Pa, 0.35 Pa, 0.4 Pa, 0.45 Pa or 0.5 Pa, etc., the power used can be 230 W, 235 W, 240 W, 245 W or 250 W, etc., and the magnetron sputtering time can be 15 min, 16 min, 17 min or 18 min, etc.

[0049] In step S4, the present invention does not limit the preparation method of the Sb2Se3 flexible thin film layer. For example, the Sb2Se3 flexible thin film layer can be formed on the second Mo thin film layer by a method of magnetron sputtering combined with selenization. Specifically, in some embodiments, the step of forming the Sb2Se3 flexible thin film layer on the second Mo thin film layer specifically includes:

[0050] Using Sb as a target, magnetron sputtering is performed on the second Mo thin film layer for 15 to 17 minutes (for example, 15, 16, or 17 minutes) at a pressure of 1.0 to 1.2 Pa (for example, 1.0 Pa, 1.05 Pa, 1.1 Pa, 1.15 Pa, or 1.2 Pa) and a power of 30 to 35 W (for example, 30 W, 31 W, 32 W, 33 W, 34 W, or 35 W) to form a Sb precursor thin film;

[0051] In an inert gas (such as argon) atmosphere and a temperature of 400-420°C (for example, 400°C, 405°C, 410°C, 415°C or 420°C), the Sb precursor film is selenized to form a Sb2Se3 flexible film layer on the second Mo film layer.

[0052] In step S5, the present invention does not limit the preparation method of the buffer layer. For example, in some embodiments, the buffer layer is formed on the Sb2Se3 flexible thin film layer by a method including but not limited to a chemical water bath deposition method.

[0053] In some embodiments, the buffer layer includes at least one of a CdS buffer layer, a ZnO buffer layer, and a SnO 2 buffer layer, but is not limited thereto.

[0054] In step S6, the present invention does not limit the preparation method of the window layer. For example, in some embodiments, the window layer is formed on the buffer layer by magnetron sputtering.

[0055] In some embodiments, the window layer includes at least one of an indium tin oxide (ITO) window layer, a fluorine-doped tin oxide (FTO) window layer, and an aluminum-doped zinc oxide (AZO) window layer, but is not limited thereto.

[0056] In step S7, the present invention does not limit the preparation method of the top electrode. For example, in some embodiments, the top electrode is formed on the window layer and the second Mo thin film layer by thermal evaporation.

[0057] In some embodiments, the top electrode includes at least one of an Ag top electrode, an Al top electrode, and a Ni top electrode, but is not limited thereto.

[0058] An embodiment of the present invention further provides an antimony selenide flexible thin film photodetector, wherein the antimony selenide flexible thin film photodetector is prepared using the method for preparing an antimony selenide flexible thin film photodetector as described above. The antimony selenide flexible thin film photodetector comprises a flexible substrate, a first Mo thin film layer, a second Mo thin film layer, an Sb2Se3 flexible thin film layer, a buffer layer, a window layer, and a top electrode located on the window layer and the second Mo thin film layer, which are stacked in sequence. The antimony selenide flexible thin film photodetector can achieve self-driven operation without an external bias voltage, with a responsivity of 0.5A / W and a detection accuracy of 10 12 Jones, for the first time, achieved nanosecond response speeds, with response times as low as 73ns and recovery times as low as 317ns. Furthermore, the flexible thin-film photodetector enables high-accuracy blood oxygen detection, with an error within 3% compared to the display of commercial oximeters.

[0059] An embodiment of the present invention further provides a use of the antimony selenide flexible thin film photodetector described above in the embodiment of the present invention in blood oxygen detection for purposes other than disease diagnosis.

[0060] An embodiment of the present invention further provides a blood oxygen detection device, wherein the blood oxygen detection device includes the antimony selenide flexible thin film photodetector described above in the embodiment of the present invention.

[0061] In some embodiments, the blood oxygen detection device also includes a signal acquisition and processing device and a light source. The signal acquisition and processing device is electrically connected to the antimony selenide flexible thin film photodetector. The light source is arranged opposite to the antimony selenide flexible thin film photodetector (during the specific test, the light emitted by the light source is partially absorbed after passing through the finger, and the light not absorbed by the finger passes through the finger and is absorbed by the antimony selenide flexible thin film photodetector). The light source emits visible light with a wavelength of 635nm and near-infrared light with a wavelength of 905nm.

[0062] The present invention will be further described below with reference to specific examples.

[0063] Example 1

[0064] This embodiment provides a method for preparing an antimony selenide flexible thin film photodetector, comprising the following steps:

[0065] Provide PI flexible substrate with a thickness of 20μm;

[0066] The PI flexible substrate was placed in a magnetron sputtering device (purchased from Shenyang Pengcheng Vacuum Technology Co., Ltd., model TCDP-II), and Mo was used as the target. Under the conditions of pressure of 1.5 Pa and power of 100 W, magnetron sputtering was performed on the flexible substrate for 25 minutes to form a first Mo thin film layer with a thickness of 300 nm.

[0067] Using Mo as a target, magnetron sputtering was performed on the first Mo thin film layer at a pressure of 0.5 Pa and a power of 250 W for 15 minutes to form a second Mo thin film layer with a thickness of 400 nm;

[0068] Using high-purity metal Sb as the target, magnetron sputtering was performed for 15 min at a pressure of 1.0 Pa and a power of 35 W to obtain a Sb precursor film.

[0069] A PI flexible substrate containing a first Mo film layer, a second Mo film layer and a Sb precursor film on the surface and 0.2g of Se powder are placed in a quartz tube of a single-temperature zone tube furnace, and a graphite block is used to fix the PI flexible substrate (in order to prevent the PI flexible substrate from being bent by heat at high temperatures), and the air pressure is evacuated to below 100Pa using a vacuum pump. Next, an inert gas, argon (Ar), is introduced into the quartz tube to maintain the air pressure at 30KPa. It is then gradually heated to 415°C at a heating rate of 20°C per minute for selenization, and maintained at this temperature for 15 minutes to ensure that selenium fully reacts with the Sb precursor. After selenization is completed, it is naturally cooled to room temperature to form a Sb2Se3 flexible film layer with a thickness of 400nm on the second Mo film layer;

[0070] Cadmium sulfate (CdSO4) and thiourea were added to water to form a mixed solution (wherein the concentration of cadmium sulfate was 0.015 mol / L and the concentration of thiourea was 0.75 mol / L), and the mixed solution was chemically deposited on the Sb2Se3 flexible thin film layer at 80°C for 9 minutes to form a CdS buffer layer with a thickness of 60 nm;

[0071] Under the conditions of pressure and power of 0.35 Pa and 120 W respectively, magnetron sputtering deposition is performed on the CdS buffer layer to form an ITO window layer with a thickness of 400 nm;

[0072] Two Ag top electrodes with a thickness of 500 nm were formed on the ITO window layer and the second Mo thin film layer by thermal evaporation to obtain the antimony selenide flexible thin film photodetector. Figure 1 As shown, the antimony selenide flexible thin film photodetector provided in this embodiment includes a PI flexible substrate, a Mo layer (wherein the Mo layer is composed of a first Mo thin film layer and a second Mo thin film layer stacked in sequence, the first Mo thin film layer is adhered to the PI flexible substrate, and the second Mo thin film layer is adhered to the Sb2Se3 flexible thin film layer), a Sb2Se3 flexible thin film layer, a CdS buffer layer, an ITO window layer, and two Ag top electrodes located on the ITO window layer and the second Mo thin film layer.

[0073] test:

[0074] (1) The photoresponsivity of the antimony selenide flexible thin film photodetector prepared in Example 1 was tested. The results are as follows: Figure 2 As shown, the antimony selenide flexible thin film photodetector can realize self-driven operation without external bias, with a response of 0.5A / W and a detection accuracy of 10 12 Jones, the response speed reached the nanosecond level for the first time, with a response time of 73 nanoseconds (corresponding to Figure 2 τ in rise ), the recovery time is 317ns (corresponding to Figure 2 τ in decay ).

[0075] (2) The antimony selenide flexible thin film photoelectric detector prepared in Example 1 is used to detect blood oxygen, as shown in the schematic diagram. Figure 3 As shown, the photoplethysmography (PPG) signal is acquired by the finger position transmission mode of the dual laser beams of 635nm visible light and 905nm near-infrared light to realize the detection of human blood oxygen. Photoplethysmography is a photoelectric technology for detecting changes in blood volume in tissue vascular beds. It has been widely used in clinical physiological monitoring, including heart rate (HR) and arterial oxygen saturation (SaO2) measurement. In the pulse oximetry sensor system, since there are significant differences in the absorption coefficients of oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (Hb) to red light and near-infrared (NIR) light, these two lights are selected as the light sources for measuring arterial oxygen saturation. The antimony selenide flexible thin film photodetector provided by the present invention shows high sensitivity in this band and is very suitable for the measurement of arterial oxygen saturation. As Figure 3 As shown, a microcontroller circuit with a power supply and a laser simultaneously emits red (635nm) and NIR (905nm) light. This incident light penetrates the finger, part of which is absorbed by HbO2 and Hb in the skin, and the rest is reflected by other tissues. The light that passes through the tissue is then detected by the flexible photodetector on the opposite side. The continuous change in arterial blood volume in the sensing area causes the light absorption in the finger to fluctuate continuously during systole and diastole, from peak to minimum. These changes in light absorption are converted into pulse signals, similar to a human heartbeat. The antimony selenide flexible photodetector converts the light signal it receives into an electrical signal through the photoelectric effect. Subsequently, a high-precision source meter is used for signal acquisition, and the photoplethysmography signal is processed and analyzed. Absorbed light (R os The ratio of ) to SaO2 value is calculated using the following formulas (1) and (2):

[0076]

[0077] Where, T rd : transmittance of red light;

[0078] Tir : transmittance of near-infrared light;

[0079] ε rd，Hb and ε ir，Hb are the molar absorption coefficients of deoxyhemoglobin for red and near-infrared light, respectively;

[0080] and are the molar absorption coefficients of oxygenated hemoglobin for red and near-infrared light, respectively.

[0081] At the same time, a commercial rigid Si photodetector and a commercial oximeter (purchased from MEDISANA, model AOJ-70C) were used to detect blood oxygen. The results are as follows: Figure 4 A comprehensive comparison shows that the blood oxygen detection results of the antimony selenide flexible thin film photodetector prepared in Example 1, namely the blood oxygen saturation value, are highly consistent with the display results of a commercial oximeter, with an error within 3%. Compared with commercial rigid Si detectors, it also shows advantages in detection accuracy and wearable flexibility.

[0082] In summary, the present invention provides an antimony selenide flexible thin film photoelectric detector, a preparation method and application thereof, and a blood oxygen detection device. The antimony selenide flexible thin film photoelectric detector prepared by the method provided by the present invention can achieve self-driven operation without external bias, with a response of 0.5A / W and a detection accuracy of 10 12 Jones, for the first time, achieved nanosecond response speeds, with response times as low as 73ns and recovery times as low as 317ns. Furthermore, the flexible thin-film photodetector can accurately measure blood oxygen levels, with an error within 3% compared to the display of a commercial oximeter.

[0083] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing an antimony selenide flexible thin film photodetector, characterized in that: The method for preparing the antimony selenide flexible thin film photodetector comprises the following steps: providing a flexible substrate; Using Mo as a target, magnetron sputtering is performed on the flexible substrate for 22 to 25 minutes at a pressure of 1.5 to 2.0 Pa and a power of 100 to 120 W to form a first Mo thin film layer; Using Mo as a target, magnetron sputtering is performed on the first Mo thin film layer for 15 to 18 minutes at a pressure of 0.3 to 0.5 Pa and a power of 230 to 250 W to form a second Mo thin film layer; forming a Sb2Se3 flexible thin film layer on the second Mo thin film layer; forming a buffer layer on the Sb2Se3 flexible thin film layer; forming a window layer on the buffer layer; A top electrode is formed on the window layer and the second Mo thin film layer to obtain the antimony selenide flexible thin film photodetector.

2. The method for preparing the antimony selenide flexible thin film photodetector according to claim 1, characterized in that: forming a buffer layer on the Sb2Se3 flexible thin film layer by a chemical water bath deposition method; The buffer layer includes at least one of a CdS buffer layer, a ZnO buffer layer, and a SnO2 buffer layer.

3. The method for preparing the antimony selenide flexible thin film photodetector according to claim 1, characterized in that: forming a window layer on the buffer layer by magnetron sputtering; The window layer includes at least one of an indium tin oxide window layer, a fluorine-doped tin oxide window layer, and an aluminum-doped zinc oxide window layer.

4. The method for preparing the antimony selenide flexible thin film photodetector according to claim 1, characterized in that: forming a top electrode on the window layer and the second Mo thin film layer by a thermal evaporation method; The top electrode includes at least one of an Ag top electrode, an Al top electrode, and a Ni top electrode.

5. The method for preparing the antimony selenide flexible thin film photodetector according to claim 1, characterized in that: The flexible substrate is one of a polyimide flexible substrate, a polyethylene terephthalate flexible substrate, a polycarbonate flexible substrate and a polyethylene naphthalate flexible substrate.

6. The method for preparing the antimony selenide flexible thin film photodetector according to claim 1, characterized in that: The step of forming the Sb2Se3 flexible thin film layer on the second Mo thin film layer specifically includes: Using Sb as a target, magnetron sputtering is performed on the second Mo thin film layer for 15 to 17 minutes at a pressure of 1.0 to 1.2 Pa and a power of 30 to 35 W to form a Sb precursor thin film; The Sb precursor film is selenized in an inert gas atmosphere at a temperature of 400-420° C. to form a Sb 2 Se 3 flexible film layer on the second Mo film layer.

7. An antimony selenide flexible thin film photodetector, characterized in that: The antimony selenide flexible thin film photoelectric detector is prepared by the preparation method of the antimony selenide flexible thin film photoelectric detector according to any one of claims 1 to 6.

8. Use of the antimony selenide flexible thin film photodetector according to claim 7 in blood oxygen detection for non-disease diagnosis purposes.

9. A blood oxygen detection device, characterized in that: The blood oxygen detection device includes the antimony selenide flexible thin film photodetector according to claim 7.

10. The blood oxygen detection device according to claim 9, characterized in that: The blood oxygen detection device also includes a signal acquisition and processing device and a light source. The signal acquisition and processing device is electrically connected to the antimony selenide flexible thin film photodetector. The light source is arranged opposite to the antimony selenide flexible thin film photodetector. The light source emits visible light with a wavelength of 635nm and near-infrared light with a wavelength of 905nm.

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