Two-dimensional black phosphorus flexible infrared detector based on photothermal effect and preparation method thereof

Abstract

The application provides a two-dimensional black phosphorus flexible infrared detector based on a photothermal effect and a preparation method thereof, and belongs to the technical field of infrared detection. The two-dimensional black phosphorus flexible infrared detector based on the photothermal effect comprises an infrared detector substrate, a source electrode, a drain electrode and a packaging layer. The infrared detector substrate comprises a polyimide substrate, a gate electrode layer, a gate oxide layer and a black phosphorus layer which are stacked in sequence. The source electrode and the drain electrode are located on the surface of the black phosphorus layer. The packaging layer is located on the side of the black phosphorus layer of the infrared detector substrate, covers the infrared detector substrate and exposes the source electrode and the drain electrode. In the application, the polyimide substrate is high in flexibility and low in thermal conductivity. When the substrate is irradiated by infrared light, the temperature of the substrate is increased, the thermal effect is enhanced, the scattering of photons is enhanced, the mobility of carriers is reduced, the negative photoconductance generated thereby is reduced, the current of the black phosphorus transistor in the on state is reduced, and the light response rate of the infrared detector is significantly improved.

Description

Technical Field

[0001] The present invention relates to the field of infrared detection technology, and in particular to a two-dimensional black phosphorus flexible infrared detector based on photothermal effect and a preparation method thereof. Background Art

[0002] Infrared detectors and infrared images have a wide range of applications in optical imaging, biomedical sensing, space exploration, and environmental monitoring. With the development of society, higher requirements are placed on the performance of detectors, requiring faster detection speeds and wider detection bands. Two-dimensional materials have attracted widespread attention due to their excellent optical, electrical, and mechanical properties. Optical prototype devices such as light-emitting diodes (LEDs), ultrafast lasers, laser modulators, and solar cells based on graphene materials have been reported in large quantities. However, due to the limitation of the zero band gap of graphene materials, the dark current of the device is large, which produces large shot noise and leads to poor detection performance of the device. The two-dimensional material transition metal chalcogenides (TMDs) have a large band gap and strong light absorption, but their response speed is slow and they cannot operate in the communication band (1550nm), making it difficult to meet the requirements of infrared detection.

[0003] Research has found that black phosphorus (bP) is a material with a tunable direct band gap from 0.3eV (bulk) to 2.0eV (monolayer), with low noise in photodetection and can be applied to the detection of visible light to infrared light. At room temperature, the carrier mobility of field-effect transistors (FETs) prepared from bP reaches 1000cm 2 / (V·s), the current modulation capability reaches 10 5 , with good retention characteristics.

[0004] However, the light response efficiency of field-effect transistors using black phosphorus as infrared detectors is poor, and the reported black phosphorus responsivity is between 4 and 150 mA / W. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a two-dimensional black phosphorus flexible infrared detector based on photothermal effect and a preparation method thereof. The two-dimensional black phosphorus flexible infrared detector based on photothermal effect provided by the present invention has good light response efficiency under infrared light irradiation.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a two-dimensional black phosphorus flexible infrared detector based on the photothermal effect, comprising an infrared detector substrate, a source electrode, a drain electrode and an encapsulation layer;

[0008] The infrared detector substrate comprises a polyimide substrate, a gate electrode layer, a gate oxide layer and a black phosphorus layer stacked in sequence;

[0009] The source electrode and the drain electrode are located on the surface of the black phosphorus layer;

[0010] The encapsulation layer is located on one side of the black phosphorus layer of the infrared detector substrate, covers the infrared detector substrate and exposes the source electrode and the drain electrode.

[0011] Preferably, the black phosphorus layer is composed of black phosphorus nanosheets, and the diameter of a single black phosphorus nanosheet is 10 to 15 μm and the thickness is 10 to 20 nm.

[0012] Preferably, the gate electrode layer includes a Ti layer and an Au layer, and the Ti layer is in contact with the polyimide substrate;

[0013] The gate oxide layer is made of Al2O3.

[0014] Preferably, the source electrode and the drain electrode are made of Au; and the encapsulation layer is made of Al2O3.

[0015] Preferably, the thickness of the polyimide substrate is 8 to 10 μm;

[0016] The thickness of the gate electrode layer is 30 to 45 nm;

[0017] The thickness of the gate oxide layer is 10 to 15 nm;

[0018] The thickness of the black phosphorus layer is 10 to 20 nm;

[0019] The thickness of the source electrode and the drain electrode is 30 to 50 nm;

[0020] The thickness of the encapsulation layer is 10-15 nm.

[0021] The present invention provides a method for preparing the above-mentioned two-dimensional black phosphorus flexible infrared detector based on the photothermal effect, comprising the following steps:

[0022] (1) loading liquid polyimide onto the surface of a substrate, heating to form a film, and obtaining a polyimide substrate on the surface of the substrate;

[0023] (2) evaporating a gate electrode raw material on the surface of the polyimide substrate to obtain a gate electrode layer on the surface of the polyimide substrate;

[0024] (3) atomically depositing a gate oxide layer on the surface of the gate electrode layer to obtain a gate oxide layer on the surface of the gate electrode layer;

[0025] (4) loading black phosphorus nanosheets on the surface of the gate oxide layer, loading photoresist on the black phosphorus nanosheets, and obtaining a black phosphorus layer covered with the photoresist on the surface of the gate oxide layer;

[0026] (5) etching the photoresist to expose source and drain electrode windows on the surface of the black phosphorus layer, evaporating source and drain electrode layers on the surface of the photoresist and the exposed windows, stripping the photoresist, and obtaining source and drain electrodes on the surface of the black phosphorus layer;

[0027] (6) atomic layer deposition of an encapsulation layer on one side of the black phosphorus layer of the infrared detector substrate, exposing the source electrode and the drain electrode during the atomic layer deposition, and obtaining an encapsulation layer on the surface of the infrared detector substrate;

[0028] (7) The substrate is removed to obtain a two-dimensional black phosphorus flexible infrared detector based on the photothermal effect.

[0029] Preferably, in step (1), the liquid polyimide is loaded onto the substrate surface by spin coating, and the spin coating speed is 2000-3000 rpm and the time is 60-90 s;

[0030] The temperature of the heating film forming is 250-300° C., and the time is 5-10 minutes.

[0031] Preferably, the evaporation temperature in step (2) and step (5) is independently 1200-1500°C, and the rate is independently The vacuum degree of the obtained evaporation is 6×10 -7 ~1×10 -6 Torr.

[0032] Preferably, the precursors of the atomic layer deposition in step (3) and step (6) are trimethylaluminum and water, the temperature of the atomic layer deposition is 120-150° C., and the time is 90-120 min.

[0033] Preferably, the method of etching the photoresist is electron beam exposure; and the method of stripping the photoresist is immersion in acetone.

[0034] The present invention provides a two-dimensional black phosphorus flexible infrared detector based on the photothermal effect, comprising an infrared detector substrate, a source electrode, a drain electrode and an encapsulation layer; the infrared detector substrate comprises a polyimide substrate, a gate electrode layer, a gate oxide layer and a black phosphorus layer stacked in sequence; the source electrode and the drain electrode are located on the surface of the black phosphorus layer; the encapsulation layer is located on one side of the black phosphorus layer of the infrared detector substrate, covering the infrared detector substrate and exposing the source electrode and the drain electrode. In the present invention, the polyimide (PI) substrate has high flexibility and low thermal conductivity. When irradiated by infrared light, the temperature of the substrate rises, generating a thermal effect that enhances the scattering of photons, thereby reducing the mobility of carriers. The resulting negative photoconductivity reduces the current of the black phosphorus transistor in the on state, significantly improving the light response rate of the infrared detector. The flexible infrared detector based on the structure of the present invention has a response rate of up to 53A / W at room temperature in the near-infrared 830nm band, and a gain of up to 8000%. In addition, the flexible detector provided by the present invention has good stability. In the 1000-fold bending test, the device still exhibits good infrared response performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the structure of a two-dimensional black phosphorus flexible infrared detector based on the photothermal effect;

[0036] Figure 2 Schematic diagram of the preparation process of two-dimensional black phosphorus flexible infrared detector based on photothermal effect;

[0037] Figure 3 : The transfer characteristic curves of the detector obtained in Example 1 under dark state and different light intensities;

[0038] Figure 4 The output characteristic curves of the detector obtained in Example 1 are in the dark state and under illumination of different intensities;

[0039] Figure 5 This is a curve showing the change in detection performance of the detector obtained in Example 1 at different bending times;

[0040] Figure 6 The dark state and light state currents of the detector obtained in Example 1 were tested before and after 1000 bends;

[0041] Figure 7 The response rate of the black phosphorus (bP) detector obtained in Comparative Example 1 based on a SiO2 / Si substrate under different light intensity conditions. DETAILED DESCRIPTION

[0042] The present invention provides a two-dimensional black phosphorus flexible infrared detector based on the photothermal effect, comprising an infrared detector substrate, a source electrode, a drain electrode and an encapsulation layer;

[0043] The infrared detector substrate comprises a polyimide substrate, a gate electrode layer, a gate oxide layer and a black phosphorus layer stacked in sequence;

[0044] The source electrode and the drain electrode are located on the surface of the black phosphorus layer;

[0045] The encapsulation layer is located on one side of the black phosphorus layer of the infrared detector substrate, covers the infrared detector substrate and exposes the source electrode and the drain electrode.

[0046] In the present invention, the infrared detector substrate comprises a polyimide substrate, a gate electrode layer, a gate oxide layer and a black phosphorus layer stacked in sequence. In the present invention, the thickness of the polyimide substrate is preferably 8 to 10 μm, more preferably 9 μm.

[0047] In the present invention, the gate electrode layer includes a Ti layer and an Au layer, with the Ti layer in contact with the polyimide substrate. The thickness of the gate electrode layer is preferably 30 to 45 nm, more preferably 41 nm. Specifically, the thickness of the Ti layer is preferably 1 nm, and the thickness of the Au layer is preferably 40 nm. In the present invention, the diameter of the gate electrode is preferably 150 to 200 μm, more preferably 160 to 180 μm.

[0048] In the present invention, the material of the gate oxide layer is preferably Al2O3, and the thickness of the gate oxide layer is preferably 10 to 15 nm, more preferably 12 to 14 nm.

[0049] In the present invention, the thickness of the black phosphorus layer is preferably 10 to 20 nm, more preferably 12 to 16 nm. In the present invention, the black phosphorus layer is composed of black phosphorus nanosheets, and the diameter of a single black phosphorus nanosheet is preferably 10 to 15 μm and the thickness is preferably 10 to 20 nm.

[0050] In the present invention, the material of the source electrode and the drain electrode is preferably Au. In the present invention, the thickness of the source electrode and the drain electrode is preferably 30 to 50 nm, more preferably 35 to 45 nm. In the present invention, the source electrode and the drain electrode are preferably located at both ends of the black phosphorus layer.

[0051] In the present invention, the material of the encapsulation layer is preferably Al2O3; the thickness of the encapsulation layer is preferably 10 to 15 nm, more preferably 12 to 14 nm.

[0052] The present invention provides a method for preparing the above-mentioned two-dimensional black phosphorus flexible infrared detector based on the photothermal effect, comprising the following steps:

[0053] (1) loading liquid polyimide onto the surface of a substrate, heating to form a film, and obtaining a polyimide substrate on the surface of the substrate;

[0054] (2) evaporating a gate electrode raw material on the surface of the polyimide substrate to obtain a gate electrode layer on the surface of the polyimide substrate;

[0055] (3) atomically depositing a gate oxide layer on the surface of the gate electrode layer to obtain a gate oxide layer on the surface of the gate electrode layer;

[0056] (4) loading black phosphorus nanosheets on the surface of the gate oxide layer, loading photoresist on the black phosphorus nanosheets, and obtaining a black phosphorus layer covered with the photoresist on the surface of the gate oxide layer;

[0057] (5) etching the photoresist to expose source and drain electrode windows on the surface of the black phosphorus layer, evaporating the source and drain electrodes on the surface of the photoresist and the exposed windows, stripping the photoresist, and obtaining the source and drain electrodes on the surface of the black phosphorus layer;

[0058] (6) atomic layer deposition of an encapsulation layer on one side of the black phosphorus layer of the infrared detector substrate, exposing the source electrode and the drain electrode during the atomic layer deposition, and obtaining an encapsulation layer on the surface of the infrared detector substrate;

[0059] (7) The substrate is removed to obtain a two-dimensional black phosphorus flexible infrared detector based on the photothermal effect.

[0060] The present invention applies liquid polyimide to a substrate surface and heats it to form a film, thereby obtaining a polyimide substrate on the substrate surface. In the present invention, the substrate is preferably a SiO2 / Si substrate. In the present invention, the liquid polyimide is applied to the substrate surface preferably by spin coating, with a spin coating speed of preferably 2000 to 3000 rpm, more preferably 2200 to 2600 rpm, and a coating time of preferably 60 to 90 seconds, more preferably 70 to 80 seconds.

[0061] In the present invention, the temperature for heating the film is preferably 250 to 300° C., more preferably 360 to 280° C.; the time is preferably 5 to 10 minutes, more preferably 6 to 8 minutes.

[0062] The present invention deposits a gate electrode material on the surface of the polyimide substrate to obtain a gate electrode layer on the surface of the polyimide substrate. In the present invention, the metal to be deposited is preferably Ti and Au. In the present invention, the temperature of the evaporation is preferably 1200-1500°C, more preferably 1300-1400°C, and the rate is preferably More preferably The vacuum degree is preferably 6×10 -7 ~1×10 -6 Torr, more preferably 8×10 -7 ~9×10 -7 Torr.

[0063] The present invention atomically deposits a gate oxide layer on the surface of the gate electrode layer to obtain a gate oxide layer on the surface of the gate electrode layer. In the present invention, the gate oxide layer is preferably made of Al2O3; when the gate oxide layer is made of Al2O3, the precursors for the atomic layer deposition are trimethylaluminum and water. In the present invention, the atomic layer deposition temperature is preferably 120-150°C, more preferably 130-140°C, and the deposition time is preferably 90-120 minutes, more preferably 100-110 minutes.

[0064] The present invention loads black phosphorus nanosheets on the surface of the gate oxide layer, coats the black phosphorus nanosheets with photoresist, and obtains a black phosphorus layer covered with photoresist on the surface of the gate oxide layer. The present invention preferably adopts a mechanical stripping method to obtain the black phosphorus nanosheets. In the present invention, the mechanical stripping is preferably: placing a thin sheet of black phosphorus block material on an adhesive tape, repeatedly gluing and folding it in half, and obtaining black phosphorus nanosheets on the surface of the adhesive tape. In the present invention, the adhesive tape is preferably a blue transparent tape. The present invention preferably transfers the black phosphorus nanosheets to the surface of the gate oxide layer by means of an adhesive tape.

[0065] In the present invention, the photoresist is preferably polymethyl methacrylate. In the present invention, the photoresist coating method is preferably spin coating. In the present invention, the spin coating speed is preferably 4000-5000 r / min, more preferably 4500 r / min. After coating the photoresist, the present invention preferably heat-cures the photoresist. The temperature of the heat-curing is preferably 175-200°C, more preferably 180-190°C, and the curing time is preferably 5-8 minutes, more preferably 6-7 minutes.

[0066] The present invention etches the photoresist, exposes the source electrode and drain electrode windows on the surface of the black phosphorus layer, evaporates the source electrode and drain electrode on the surface of the photoresist and the exposed window, peels off the photoresist, and obtains the source electrode and drain electrode on the surface of the black phosphorus layer. In the present invention, the method of etching the photoresist is electron beam exposure. In the present invention, the evaporated metal is preferably Au. In the present invention, the evaporation temperature is preferably 1200-1500°C, more preferably 1300-1400°C, and the rate is preferably More preferably The vacuum degree is preferably 6×10 -7 ~1×10 -6 Torr, more preferably 8×10 -7 ~9×10 -7 Torr.

[0067] In the present invention, the method of stripping the photoresist is preferably immersing in acetone. In the present invention, the immersion time is preferably 10 to 30 minutes, more preferably 15 to 25 minutes.

[0068] The present invention atomically layers an encapsulation layer onto one side of the black phosphorus layer of the infrared detector substrate. The source and drain electrodes are exposed during the atomic layer deposition, thereby obtaining an encapsulation layer on the surface of the infrared detector substrate. In the present invention, the material of the encapsulation layer is preferably Al2O3; when the material of the encapsulation layer is Al2O3, the precursors of the atomic layer deposition are trimethylaluminum and water. In the present invention, the temperature of the atomic layer deposition is preferably 150°C, and the time is preferably 90 to 120 minutes, more preferably 100 to 110 minutes.

[0069] The present invention removes the substrate to obtain a two-dimensional black phosphorus flexible infrared detector based on the photothermal effect. The present invention has no special requirements for the method of removing the substrate, and a method of removing the substrate well known to those skilled in the art can be used.

[0070] In the present invention, the structural diagram of the two-dimensional black phosphorus flexible infrared detector based on the photothermal effect is as follows Figure 1 The preparation process diagram is shown in Figure 2 shown. Figure 1 In the figure, 1 is a polyimide substrate, 2 is a gate electrode layer, 3 is a gate oxide layer, 4 is a black phosphorus layer, 5 is a source electrode, 6 is a drain electrode, and 7 is an encapsulation layer; Figure 2 In the figure, 8 is a Si substrate and 9 is a SiO2 substrate.

[0071] The two-dimensional black phosphorus flexible infrared detector based on the photothermal effect and the preparation method thereof provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0072] Example 1

[0073] The preparation method of the two-dimensional black phosphorus flexible infrared detector based on the photothermal effect is as follows:

[0074] Liquid polyimide (PI) was spin-coated onto the SiO2 / Si substrate at a speed of 2000 r / min and then heated on a 300°C hot plate for 1 hour to form a 10 μm thick flexible film. Using a mask, a 1 nm / 40 nm Ti / Au gate electrode layer was deposited on the PI film by thermal evaporation. The electrode diameter was 150 μm and the vacuum degree of the evaporation was 6×10 -7 Torr, the temperature is 1500 ° C. Then, a 15nm Al2O3 gate oxide layer is deposited on the gate electrode layer by atomic layer deposition (ALD). The precursors of the atomic layer deposition are trimethylaluminum and water, and the deposition temperature is 150 ° C.

[0075] The bulk black phosphorus material was mechanically stripped into layered black phosphorus flakes, which were then immersed in a hot acetone solution for 1 hour to remove any tape residue from the surface. The black phosphorus flakes were then transferred to the gate oxide layer. A PMMA solution was then spin-coated on the device surface at a speed of 5000 rpm and baked at 175°C for 5 minutes to form a photoresist layer. Electron beam lithography (EBL) was used to locate the source and drain electrode windows, followed by evaporation of a 50nm gold film at a vacuum of 6×10 -7 Torr, the temperature is 1500℃.

[0076] The source and drain metal electrodes were formed by stripping in an acetone solution. Atomic layer deposition (ALD) was used to deposit an Al2O3 oxide layer to encapsulate the black phosphorus device. The ALD precursors were trimethylaluminum and water at a deposition temperature of 150°C. Finally, the PI substrate was separated from the SiO2 / Si surface to yield a two-dimensional black phosphorus flexible infrared detector based on the photothermal effect.

[0077] The transfer characteristic curves of the obtained detector in dark state and under different light intensities are shown as follows: Figure 3 As shown, the output characteristic curve is as follows Figure 4 As shown. Figure 3 and 4 It can be seen that under the irradiation of 830nm infrared light, with the light intensity of 11.9W / cm 2 、13.5W / cm 2 、14.9W / cm 2 、16.5W / cm 2 Compared with the dark state, the current in the on state decreases. Under light conditions, the stronger the light, the higher the temperature of the PI substrate, the stronger the photon scattering, which reduces the on-state current of the device and improves the detection performance of the device. 2 Under the conditions of , an ultra-high response rate of 53A / W is obtained.

[0078] The curve of the detector's detection performance at different bending times is shown in the figure below: Figure 5 As shown. Figure 5 It can be seen that after multiple bends, the on / off ratio of the device remains at 10 3 The device mobility is maintained at 100-150cm 2 / (V·s) range, showing excellent device stability.

[0079] The dark state and light state currents of the obtained detector were tested before and after 1000 bending cycles. Figure 6 As shown. Figure 6 It can be seen that the dark state current and light state current of the test device do not change much before and after 1000 bending cycles, indicating that the device has good flexibility.

[0080] Comparative Example 1

[0081] A black phosphorus (bP) detector without spin-coating PI was prepared on a SiO2 / Si substrate. The specific operation was the same as in Example 1, except that liquid polyimide was not spin-coated, and a 1nm / 40nm Ti / Au gate electrode layer was directly evaporated on the substrate.

[0082] The black phosphorus (bP) detector obtained in Comparative Example 1 was subjected to a photocurrent test, and the results showed that no photothermal effect occurred. Under illumination conditions, the photocurrent was significantly weaker than that of the two-dimensional black phosphorus flexible infrared detector based on the photothermal effect obtained in Example 1.

[0083] The response rate of the black phosphorus (bP) detector obtained in comparative example 1 based on SiO2 / Si substrate under different light intensity conditions was tested. Figure 7 As shown, the results show that at 4.7W / cm 2 、11.9W / cm 2 、14.9W / cm 2 、18.2W / cm 2 The obtained responsivities were 1.30 A / W, 0.64 A / W, 0.57 A / W, and 0.56 A / W, respectively, which were significantly lower than those of the two-dimensional black phosphorus flexible infrared detector based on the photothermal effect obtained in Example 1. This is mainly due to the large thermal conductivity of the SiO2 / Si substrate, which cannot produce the performance of reducing the device resistance due to the thermal effect.

[0084] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A two-dimensional black phosphorus flexible infrared detector based on the photothermal effect, comprising an infrared detector substrate, a source electrode, a drain electrode, and an encapsulation layer; The infrared detector substrate comprises a polyimide substrate, a gate electrode layer, a gate oxide layer and a black phosphorus layer stacked in sequence; The source electrode and the drain electrode are located on the surface of the black phosphorus layer; The encapsulation layer is located on one side of the black phosphorus layer of the infrared detector substrate, covers the infrared detector substrate and exposes the source electrode and the drain electrode; The gate electrode layer includes a Ti layer and an Au layer, and the Ti layer is in contact with the polyimide substrate; the gate oxide layer is made of Al2O3; The thickness of the polyimide substrate is 8 to 10 μm; The thickness of the gate electrode layer is 30 to 45 nm; The thickness of the gate oxide layer is 10 to 15 nm; The thickness of the black phosphorus layer is 10 to 20 nm; The thickness of the source electrode and the drain electrode is 30 to 50 nm; The thickness of the encapsulation layer is 10-15 nm.

2. The two-dimensional black phosphorus flexible infrared detector based on the photothermal effect according to claim 1 is characterized in that: The black phosphorus layer is composed of black phosphorus nanosheets. The diameter of a single black phosphorus nanosheet is 10 to 15 μm and the thickness is 10 to 20 nm.

3. The two-dimensional black phosphorus flexible infrared detector based on the photothermal effect according to claim 1 is characterized in that: The source electrode and the drain electrode are made of Au; the encapsulation layer is made of Al2O3.

4. The method for preparing a two-dimensional black phosphorus flexible infrared detector based on the photothermal effect according to any one of claims 1 to 3, comprising the following steps: (1) loading liquid polyimide onto the surface of a substrate, heating to form a film, and obtaining a polyimide substrate on the surface of the substrate; (2) evaporating a gate electrode raw material on the surface of the polyimide substrate to obtain a gate electrode layer on the surface of the polyimide substrate; (3) atomically depositing a gate oxide layer on the surface of the gate electrode layer to obtain a gate oxide layer on the surface of the gate electrode layer; (4) loading black phosphorus nanosheets on the surface of the gate oxide layer, loading photoresist on the black phosphorus nanosheets, and obtaining a black phosphorus layer covered with the photoresist on the surface of the gate oxide layer; (5) etching the photoresist to expose source and drain electrode windows on the surface of the black phosphorus layer, evaporating source and drain electrode layers on the surface of the photoresist and the exposed windows, stripping the photoresist, and obtaining source and drain electrodes on the surface of the black phosphorus layer; (6) atomic layer deposition of an encapsulation layer on one side of the black phosphorus layer of the infrared detector substrate, exposing the source electrode and the drain electrode during the atomic layer deposition, and obtaining an encapsulation layer on the surface of the infrared detector substrate; (7) The substrate is removed to obtain a two-dimensional black phosphorus flexible infrared detector based on the photothermal effect.

5. The preparation method according to claim 4, characterized in that In the step (1), the liquid polyimide is loaded onto the substrate surface by spin coating at a rate of 2000 to 3000 rpm for 60 to 90 seconds. The temperature of the heating film forming is 250-300° C., and the time is 5-10 minutes.

6. The preparation method according to claim 4, characterized in that The evaporation temperature in step (2) and step (5) is independently 1200-1500°C, and the rate is independently The vacuum degree of the obtained evaporation is 6×10 -7 ~1×10 - 6 Torr.

7. The preparation method according to claim 4, characterized in that The precursors of the atomic layer deposition in step (3) and step (6) are trimethylaluminum and water, the temperature of the atomic layer deposition is 120-150° C., and the time is 90-120 min.

8. The preparation method according to claim 4, characterized in that The method of etching the photoresist is electron beam exposure; the method of stripping the photoresist is immersion in acetone.

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