1. A heterojunction-based high efficiency photodetector, comprising: an electrolyte bath, a reference electrode, a counter electrode, and a heterojunction-based working electrode; electrolyte is arranged in the electrolyte tank, the reference electrode, the working electrode and the counter electrode are sequentially arranged on the surface of the electrolyte tank, the reference electrode, the working electrode and the counter electrode all extend into the electrolyte, wherein the working electrode comprises: a substrate, a bismuth-series compound film and a tin disulfide structure; the bismuth-series compound film is arranged on one side of the substrate, and the tin disulfide structures are vertically arranged on one side, away from the substrate, of the bismuth-series compound film; one end of the working electrode, which penetrates into the electrolyte, is opposite to the light-transmitting window on the electrolyte tank.

2. The heterojunction-based high-efficiency photodetector of claim 1, wherein the material of the bismuth-series compound thin film comprises any one of bismuth telluride and bismuth selenide.

3. A high efficiency photodetector based on a heterojunction as claimed in claim 2 wherein said substrate has a thickness of 0.5mm to 0.8mm, a length of 85mm to 120mm and a width of 85mm to 120 mm.

4. The heterojunction-based high efficiency photodetector of claim 3, wherein the material of the reference electrode is silver-silver chloride.

5. A heterojunction-based high efficiency photodetector as claimed in claim 4, wherein the material of said counter electrode is platinum.

6. A method for preparing a heterojunction of a heterojunction-based high-efficiency photoelectric detector is characterized by comprising the following steps:

disposing a bismuth-series compound and a substrate inside a quartz tube;

heating a region corresponding to the bismuth-series compound in the quartz tube to a preset first temperature, blowing argon gas to the position of the substrate from the direction of the bismuth-series compound, and depositing on the substrate to obtain a bismuth-series compound film;

arranging SnCl4 & 5H2O and sulfur powder on one side of the substrate in sequence inside the quartz tube;

and heating the quartz tube to a preset second temperature, and introducing gas from the sulfur powder direction to the bismuth series compound substrate direction by using argon gas, so that the surface of the bismuth series compound film on the substrate is deposited to form a tin disulfide structure.

7. The method of claim 6, further comprising, after the step of disposing a bismuth-series compound and a substrate inside the quartz tube:

pumping the pressure in the quartz tube to be below 100Pa by using a vacuum pump;

argon gas was blown from the direction of the bismuth-series compound to the substrate position for 5 minutes.

8. The method of claim 7, wherein the step of disposing SnCl 4-5H 2O and sulfur powder sequentially on one side of the substrate inside the quartz tube further comprises:

pumping the pressure in the quartz tube to be below 100Pa by using a vacuum pump;

argon gas was introduced from the sulfur powder direction to the bismuth-series compound substrate direction for 5 minutes.

9. The method for preparing the heterojunction of the heterojunction-based high-efficiency photoelectric detector according to claim 8, wherein the preset first temperature is 450 ℃ to 550 ℃, and the preset second temperature is 200 ℃ to 450 ℃.

Background

Photodetection is a process of converting optical signals into electrical signals, which plays a crucial role in technical applications such as sensing, communication and spectroscopy. The transition metal disulfide in the prior art has high carrier mobility, strong photo-substance interaction and large specific surface area, has faster separation and transmission efficiency of electron-hole pairs, and is suitable for PEC type photodetectors.

However, due to the influence of the structure or the material, the photoelectric performance of the photoelectric detector in the prior art is poor, and the photoelectric response is low, so that the accuracy and the sensitivity of the photoelectric detector in the prior art are not sufficient, and the photoelectric detector in the prior art is difficult to be applied in an application environment requiring high sensitivity and high accuracy.

Disclosure of Invention

The invention aims to provide a high-efficiency photoelectric detector based on a heterojunction and a preparation method of the heterojunction, aiming at overcoming the defects in the prior art, so that the photoelectric performance of the photoelectric detector in the prior art is poor due to the influence of the structure or materials of the photoelectric detector in the prior art, the photoelectric response is low, the accuracy and the sensitivity of the photoelectric detector in the prior art are insufficient, and the photoelectric detector is difficult to apply to an application environment requiring high sensitivity and high accuracy.

In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solutions:

in a first aspect, the present application provides a heterojunction-based high efficiency photodetector, comprising: an electrolyte bath, a reference electrode, a counter electrode, and a heterojunction-based working electrode; be provided with electrolyte in the electrolyte tank, reference electrode, working electrode and counter electrode set gradually on the electrolyte tank surface, and reference electrode, working electrode and counter electrode all extend to electrolyte in, wherein, working electrode includes: a substrate, a bismuth-series compound film and a tin disulfide structure; a bismuth series compound film is arranged on one side of the substrate, and a tin disulfide structure is vertically arranged on one side of the bismuth series compound film, which is far away from the substrate; one end of the working electrode, which extends into the electrolyte, is opposite to the light-transmitting window on the electrolyte tank.

Alternatively, the material of the bismuth-series compound thin film includes any one of bismuth telluride and bismuth selenide.

Optionally, the substrate has a thickness of 0.5mm to 0.8mm, a length of 85mm to 120mm, and a width of 85mm to 120 mm.

Optionally, the material of the reference electrode is silver-silver chloride.

Optionally, the material of the pair of electrodes is platinum.

In a second aspect, the present application provides a method for preparing a heterojunction of a heterojunction-based high-efficiency photodetector, the method comprising:

disposing a bismuth-series compound and a substrate inside a quartz tube;

heating a region corresponding to the bismuth series compound in the quartz tube to a preset first temperature, blowing argon to the position of a substrate from the direction of the bismuth series compound, and depositing on the substrate to obtain a bismuth series compound film;

SnCl4 & 5H2O and sulfur powder are sequentially arranged on one side of a substrate in a quartz tube;

and heating the quartz tube to a preset second temperature, and introducing gas from the direction of sulfur powder to the direction of the bismuth series compound substrate by using argon gas, so that the surface of the bismuth series compound film on the substrate is deposited to form a tin disulfide structure.

Optionally, the step of disposing a bismuth-series compound and a substrate inside the quartz tube further comprises:

pumping the pressure in the quartz tube to be below 100Pa by using a vacuum pump;

argon gas was blown from the direction of the bismuth-series compound to the substrate position for 5 minutes.

Optionally, the step of disposing the SnCl4 · 5H2O and the sulfur powder sequentially on one side of the substrate inside the quartz tube further comprises:

pumping the pressure in the quartz tube to be below 100Pa by using a vacuum pump;

argon gas was introduced into the bismuth-series compound substrate from the sulfur powder direction for 5 minutes.

Optionally, the preset first temperature is 450 ℃ to 550 ℃, and the preset second temperature is 200 ℃ to 450 ℃.

The invention has the beneficial effects that:

the application provides a high-efficient photoelectric detector based on heterojunction, photoelectric detector includes: an electrolyte bath, a reference electrode, a counter electrode, and a heterojunction-based working electrode; be provided with electrolyte in the electrolyte tank, reference electrode, working electrode and counter electrode set gradually on the electrolyte tank surface, and reference electrode, working electrode and counter electrode all extend to electrolyte in, wherein, working electrode includes: a substrate, a bismuth-series compound film and a tin disulfide structure; a bismuth series compound film is arranged on one side of the substrate, and a tin disulfide structure is vertically arranged on one side of the bismuth series compound film, which is far away from the substrate; one end of the working electrode extending into the electrolyte is opposite to the light-transmitting window on the electrolyte tank; because the tin disulfide structure vertical arrangement on the bismuth series compound film in photoelectric detector's the heterojunction of this application, make tin disulfide structure have great specific surface area, and form van der Waals heterojunction with bismuth series compound film, and then make when detecting optical signal, accelerate the separation and the transmission of photogenerated carrier, thereby improve photoelectric detector's of this application photoelectric response, and thereby make photoelectric detector's of this application detection accuracy and sensitivity all obtain great improvement, and then make photoelectric detector of this application can use in the application environment of demand high sensitivity and high accuracy.

The application provides a preparation method of a heterojunction of a high-efficiency photoelectric detector based on the heterojunction, which comprises the following steps: disposing a bismuth-series compound and a substrate inside a quartz tube; heating a region corresponding to the bismuth series compound in the quartz tube to a preset first temperature, blowing argon to the position of a substrate from the direction of the bismuth series compound, and depositing on the substrate to obtain a bismuth series compound film; SnCl4 & 5H2O and sulfur powder are sequentially arranged on one side of a substrate in a quartz tube; heating the quartz tube to a preset second temperature, ventilating the bismuth-series compound substrate from the direction of sulfur powder by using argon gas, and depositing the surface of the bismuth-series compound film on the substrate to form a tin disulfide structure, namely, the heterojunction of the photoelectric detector prepared by the simple steps is used in the method, because the tin disulfide structure on the bismuth-series compound film in the heterojunction of the photoelectric detector is vertically arranged, the tin disulfide structure has a large specific surface area and forms a Van der Waals heterojunction with the bismuth-series compound film, and further when detecting optical signals, the separation and transmission of photon-generated carriers are accelerated, so that the photoelectric response of the photoelectric detector is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a schematic structural diagram of a high-efficiency heterojunction-based photodetector according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a heterojunction-based high-efficiency photodetector according to an embodiment of the present invention;

FIG. 3 is a schematic flow chart of a method for fabricating a heterojunction of a heterojunction-based high-efficiency photodetector according to an embodiment of the present invention;

FIG. 4 is a schematic flow chart of another method for fabricating a heterojunction of a heterojunction-based high-efficiency photodetector according to an embodiment of the present invention;

FIG. 5 is a schematic flow chart of another method for fabricating a heterojunction of a heterojunction-based high-efficiency photodetector according to an embodiment of the present invention;

FIG. 6 is a Raman spectrum of a Bi2Te3, SnS2 and SnS2/Bi2Te3 heterojunction;

FIG. 7 is a Raman spectrum of a Bi2Se3, SnS2 and SnS2/Bi2Se3 heterojunction;

FIG. 8 is a plot of photocurrent density as a function of light on/dark at-0.1V bias for a PEC-type photodetector based on a SnS2/Bi2X3 heterojunction made in accordance with the present invention;

FIG. 9 is a bar graph of the photoresponse of a PEC-type photodetector based on a SnS2/Bi2X3 heterojunction made in accordance with the present invention at-0.1V bias;

FIG. 10 is a plot of photocurrent density as a function of light on/dark at 0V bias for a PEC-type photodetector based on an SnS2/Bi2X3 heterojunction made in accordance with the present invention;

FIG. 11 is a graph of photocurrent density at different wavelengths (420nm, 450nm, 475nm, 500nm, 550nm, 600nm, and 650nm) for a PEC-type photodetector based on a SnS2/Bi2X3 heterojunction made in accordance with the present invention;

fig. 12 is a graph of photocurrent density and photoresponse rate of the SnS2/Bi2Se3 and the SnS2/Bi2Te3 heterojunction of the heterojunction-based high-efficiency photodetector provided by the embodiment of the invention at different wavelengths.

Icon: 10-an electrolyte bath; 20-a reference electrode; 30-a working electrode; 31-a substrate; a 32-bismuth series compound thin film; a 33-tin disulfide structure; 40-pairs of electrodes.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are one embodiment of the present invention, and not all embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

Furthermore, the terms "horizontal", "vertical" and the like do not imply that the components are required to be absolutely horizontal or pendant, but rather may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In order to make the implementation of the present invention clearer, the following detailed description is made with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of a high-efficiency heterojunction-based photodetector according to an embodiment of the present invention; FIG. 2 is a schematic structural diagram of a heterojunction-based high-efficiency photodetector according to an embodiment of the present invention; as shown in fig. 1 and 2, the present application provides a heterojunction-based high-efficiency photodetector, including: an electrolyte bath 10, a reference electrode 20, a counter electrode 40, and a heterojunction-based working electrode 30; electrolyte is arranged in the electrolyte tank 10, the reference electrode 20, the working electrode 30 and the counter electrode 40 are sequentially arranged on the surface of the electrolyte tank 10, and the reference electrode 20, the working electrode 30 and the counter electrode 40 all extend into the electrolyte, wherein the working electrode 30 comprises: a substrate 31, a bismuth-series compound thin film 32, and a tin disulfide structure 33; a bismuth series compound film 32 is arranged on one side of the substrate 31, and tin disulfide structures 33 are vertically arranged on one side, far away from the substrate 31, of the bismuth series compound film 32; the end of the working electrode 30 that extends into the electrolyte is opposite the light-transmissive window in the electrolyte bath 10.

The electrolyte tank 10 is provided with an electrolyte, the type and specific amount of the electrolyte are determined according to actual needs, and are not specifically limited herein, in practical application, the electrolyte tank is provided with three electrodes, the three electrodes are respectively a reference electrode 20, a working electrode 30 and a counter electrode 40, the materials and dimensions of the reference electrode 20, the working electrode 30 and the counter electrode 40 are determined according to actual needs, and are not specifically limited herein, the reference electrode 20, the working electrode 30 and the counter electrode 40 are all electrically connected with the outside, in practical application, the substrate 31 is a conductive substrate 31, the substrate 31 can be selected from an indium-doped tin oxide transparent conductive ITO substrate 31 or a fluorine-doped tin oxide transparent conductive FTO substrate 31, one end of the reference electrode 20, one end of the working electrode 30 and one end of the counter electrode 40 are electrically connected with the outside, the other end of the reference electrode is immersed in the electrolyte, one end of the working electrode 30, which is deep into the electrolyte, is provided with a heterojunction, the heterojunction comprises a substrate 31, a bismuth-series compound film 32 and a tin disulfide structure 33, wherein the substrate 31 is used for receiving the bismuth-series compound film 32 and the tin disulfide structure 33, the bismuth-series compound film 32 is arranged on the substrate 31, the tin disulfide structure 33 is arranged on the surface of the bismuth-series compound film 32, the tin disulfide structure 33 is arranged perpendicular to the bismuth-series compound film 32, the corresponding positions of the tin disulfide structure 33 and the electrolyte tank 10 are made of light-transmitting materials, the shell of the electrolyte tank 10 can be made of transparent materials, the positions of the tin disulfide structure 33 and the electrolyte tank 10 are made of light-transmitting materials, light to be measured enters the electrolyte tank 10 through the light-transmitting parts and acts on the heterojunction, and the tin disulfide structure 33 on the bismuth-series compound film 32 in the heterojunction of the photoelectric detector of the application is vertically arranged on the tin disulfide structure 33 The tin disulfide structure 33 has a large specific surface area and forms a van der waals heterojunction with the bismuth-series compound film 32, so that separation and transmission of a photon-generated carrier are accelerated when an optical signal is detected, the photoelectric response of the photoelectric detector is improved, the detection accuracy and sensitivity of the photoelectric detector are greatly improved, and the photoelectric detector can be applied to application environments requiring high sensitivity and high accuracy; in practical applications, the bismuth-based compound thin film 32 provided on one side of the substrate 31 is formed by growing the bismuth-based compound thin film 32 on the surface of the substrate 31.

Alternatively, the material of the bismuth-series compound thin film 32 includes any one of bismuth telluride and bismuth selenide.

The bismuth series compound thin film 32 may be made of bismuth telluride or bismuth selenide, that is, the heterojunction has a structure in which the bismuth series compound thin film 32 made of bismuth telluride is disposed on the substrate 31, and a tin disulfide structure 33 is vertically disposed on the surface of the bismuth series compound thin film 32 made of bismuth telluride, or the heterojunction has a structure in which the bismuth series compound thin film 32 made of bismuth selenide is disposed on the substrate 31 and a tin disulfide structure 33 is vertically disposed on the surface of the bismuth series compound thin film 32 made of bismuth selenide; in practical application, both bismuth telluride and bismuth selenide materials can be used as the materials of the bismuth series compound thin film 32 of the heterojunction, and the bismuth telluride and the bismuth selenide can be used to ensure that the tin disulfide structure 33 is uniformly arranged on the surface of the bismuth series compound thin film 32; in order to further explain the characteristics and differences of bismuth telluride and bismuth selenide materials, a heterojunction made of the bismuth selenide material is called an I-type heterojunction, a heterojunction made of the bismuth telluride material is called a II-type heterojunction, and the performance of the PEC-type photodetector is improved by designing the I-type and II-type heterostructures. Using experimental data for specification;

optionally, the substrate 31 has a thickness of 0.5mm to 0.8mm, a length of 85mm to 120mm, and a width of 85mm to 120 mm.

The thickness of the substrate 31 can be 0.5mm, 0.8mm, or any size between 0.5mm and 0.8mm, and the length of the substrate 31 can be 85mm, 120mm, or any size between 85mm and 120 mm; the thickness of the substrate 31 may be 85mm, 120mm, or any size between 85mm and 120mm, and the length and width of the substrate 31 are substantially equal to those of the bismuth-series compound thin film 32 provided on the substrate 31.

Optionally, the material of the reference electrode 20 is silver-silver chloride.

The material of the reference electrode 20 is a mixed material of silver and silver chloride.

Optionally, the material of the pair of electrodes 40 is platinum.

The application provides a high-efficient photoelectric detector based on heterojunction, photoelectric detector includes: an electrolyte bath 10, a reference electrode 20, a working electrode 30, a counter electrode 40, and a heterojunction; be provided with electrolyte in the electrolyte groove 10, reference electrode 20, working electrode 30 and counter electrode 40 set gradually on the electrolyte groove 10 surface, and reference electrode 20, working electrode 30 and counter electrode 40 all extend to electrolyte, and the heterojunction setting is deepened at working electrode 30 one end of electrolyte, and wherein, the heterojunction includes: a substrate 31, a bismuth-series compound thin film 32, and a tin disulfide structure 33; a bismuth series compound film 32 is arranged on one side of the substrate 31, a tin disulfide structure 33 is arranged on one side, away from the substrate 31, of the bismuth series compound film 32, the tin disulfide structure 33 is vertically arranged on the bismuth series compound film 32, and a light-transmitting window is arranged at the position, corresponding to the electrolyte tank 10, of the tin disulfide structure 33 and is generally made of a light-transmitting material; because tin disulfide structure 33 on the bismuth series compound film 32 in photoelectric detector's the heterojunction of this application sets up perpendicularly, make tin disulfide structure 33 have great specific surface area, and form van der Waals heterojunction with bismuth series compound film 32, and then make when detecting optical signal, accelerate the separation and the transmission of photocarrier, thereby improve photoelectric detector's of this application photoelectric response, and thereby make photoelectric detector's of this application detection accuracy and sensitivity all obtain great improvement, and then make photoelectric detector of this application can use in the application environment of demand high sensitivity and high accuracy.

FIG. 3 is a schematic flow chart of a method for fabricating a heterojunction of a heterojunction-based high-efficiency photodetector according to an embodiment of the present invention; as shown in fig. 3, the present application provides a method for preparing a heterojunction of a heterojunction-based high-efficiency photodetector, the method comprising:

s101, arranging a bismuth series compound and a substrate in the quartz tube.

The bismuth-series compound and the substrate are respectively arranged in the quartz tube, and because both ends of the quartz tube are generally provided with openings, the order and the positions of the bismuth-series compound and the substrate are determined according to actual requirements, and are not particularly limited herein.

S102, heating a region corresponding to the bismuth series compound in the quartz tube to a preset first temperature, blowing argon to the position of the substrate from the direction of the bismuth series compound, and depositing on the substrate to obtain the bismuth series compound film.

Because the bismuth-series compound and the substrate are arranged in the quartz tube, the area where the bismuth-series compound is arranged is divided into an upstream temperature zone, the position where the substrate is arranged is set as a downstream temperature zone, the quartz tube is arranged on a heating device, the upstream temperature zone is heated to a preset first temperature by the quartz tube, the bismuth-series compound is gasified in a high-temperature environment, the bismuth-series compound is required to be gasified, the preset first temperature is higher than the gasification temperature of the bismuth-series compound, the gasified bismuth-series compound is blown onto the substrate in the downstream temperature zone from the upstream temperature zone by using argon, and because the temperature in the downstream temperature zone is lower than that in the upstream temperature zone, the gasified bismuth-series compound meets the substrate and is cooled on the surface of the substrate, so that the surface of the substrate is uniformly covered with a bismuth-series compound film, the amount of the bismuth-series compound is determined according to actual needs, and in practical application, the amount of the bismuth-series compound can cover the surface of the substrate after the bismuth-series compound is cooled on the surface of the substrate.

S103, SnCl4 & 5H2O and sulfur powder are sequentially arranged on one side of the substrate in the quartz tube.

The SnCl 4.5H 2O and the sulfur powder are sequentially arranged on one side of the substrate in the quartz tube, namely, the SnCl 4.5H 2O and the sulfur powder are sequentially arranged on one side of the substrate, in practical application, a certain distance is arranged among the substrate, the SnCl 4.5H 2O and the sulfur powder, the distance among the substrate, the SnCl 4.5H 2O and the sulfur powder is determined according to practical requirements and is not particularly limited, and the specific amounts of the SnCl 4.5H 2O and the sulfur powder are determined according to practical requirements and are not particularly limited.

And S104, heating the quartz tube to a preset second temperature, and ventilating argon gas from the direction of the sulfur powder to the direction of the bismuth series compound substrate to deposit the surface of the bismuth series compound film on the substrate to form a tin disulfide structure.

Dividing an SnCl4 & 5H2O area and a sulfur powder area in the quartz tube into an upstream temperature area, dividing the substrate position into a downstream temperature area, heating the upstream temperature area in the quartz tube to enable the SnCl4 & 5H2O and the sulfur powder to react to generate tin disulfide, blowing the tin disulfide generated by the reaction to the substrate direction by using argon, wherein the substrate is at the downstream temperature area position, the temperature of the downstream temperature area is lower than that of the tin disulfide, the generated tin disulfide can be condensed on the substrate surface to form a tin disulfide structure, the tin disulfide structure is perpendicular to the bismuth series compound film, and a heterojunction is formed between the bismuth series compound film and the tin disulfide structure.

FIG. 4 is a schematic flow chart of another method for fabricating a heterojunction of a heterojunction-based high-efficiency photodetector according to an embodiment of the present invention; as shown in fig. 4, the step of disposing a bismuth-series compound and a substrate inside the quartz tube optionally further includes:

s201, using a vacuum pump to pump the pressure in the quartz tube to be less than 100 Pa.

S202, argon gas was blown to the substrate from the direction of the bismuth-series compound for 5 minutes.

In order to remove the impurity air from the inside of the quartz tube, the pressure of the quartz tube was forcibly reduced to 100Pa or less by a vacuum pump, and then the argon gas valve was opened and the substrate position was ventilated with argon gas for 5 minutes from the direction of the bismuth series compound to exhaust the residual air in the apparatus.

Optionally, the post-reaction after the 5 minute step of blowing argon gas from the direction of the bismuth-series compound toward the substrate position further comprises: continuously introducing argon gas of 20-40 sccm into the quartz tube until the reaction is finished.

Alternatively, after blowing argon gas to the substrate position from the direction of the bismuth-series compound for 5 minutes, it is generally necessary to continuously open the vacuum pump, adjust the gas flow rate to 35sccm, and perform continuous argon gas blowing.

FIG. 5 is a schematic flow chart of another method for fabricating a heterojunction of a heterojunction-based high-efficiency photodetector according to an embodiment of the present invention; as shown in fig. 5, the step of disposing SnCl4 · 5H2O and sulfur powder in sequence on one side of the substrate inside the quartz tube optionally further comprises:

s301, using a vacuum pump to pump the pressure in the quartz tube to be less than 100 Pa.

S302, an air flow was conducted for 5 minutes from the sulfur powder direction toward the bismuth-series compound substrate using argon gas.

In order to remove the impurity air inside the quartz tube, the pressure of the quartz tube was forcibly evacuated to 100Pa or less by a vacuum pump, and then an argon gas valve was opened and an argon gas was introduced from the sulfur powder direction to the position of the bismuth-series compound substrate for 5 minutes to exhaust the residual air inside the apparatus.

Alternatively, after blowing argon gas to the substrate position from the direction of the bismuth-series compound for 5 minutes, it is generally necessary to continuously open the vacuum pump, adjust the gas flow rate to 35sccm, and perform continuous argon gas blowing.

Optionally, the preset first temperature is 450 ℃ to 550 ℃, and the preset second temperature is 200 ℃ to 450 ℃.

The heterojunction in this application can be under the condition of no external power supply bias voltage, and when the heterojunction was immersed in electrolyte as working electrode, illumination passed through the transparent window on the electrolysis trough and shone on the electrically conductive substrate that has the heterojunction long. Under the condition of adding-0.1V bias voltage, the change of photocurrent response is measured in the process of on-light (bright environment) and off-light (dark environment) circulation, and the Raman spectra of Bi2Te3, SnS2 and SnS2/Bi2Te3 heterojunction are shown in figure 6; as shown in FIG. 6, the characteristic peaks of Bi2Te3 in the vicinity of 100cm-1 and 138cm-1 correspond to the Eg and A1g vibrational modes thereof, respectively. The SnS2/Bi2Te3 heterostructure has three characteristic peaks at 99cm-1, 139cm-1 and 311cm-1, which respectively correspond to the Eg and A1g vibration modes of Bi2Te3 and the A1g vibration mode of SnS 2. Therefore, the heterojunction prepared is an SnS2/Bi2Te3 heterojunction (the preparation success of the SnS2/Bi2Te3 heterojunction is shown); when light is irradiated, the photocurrent density is obviously greater than that when the light is not irradiated; the photocurrent density at the light/dark cycle was still detected when no external bias was applied. The photoelectric detection can still be carried out under the condition of no external bias voltage, so that the photoelectric detection is further carried out under certain specific conditions (without an external power supply), and the photoelectric detection has better environmental adaptability and flexibility.

FIG. 7 is a Raman spectrum of a Bi2Se3, SnS2 and SnS2/Bi2Se3 heterojunction; as shown in FIG. 7, the characteristic peaks of Bi2Se3 in the vicinity of 129cm-1 and 174cm-1 correspond to the Eg and A1g vibration modes thereof, respectively. The characteristic peak of the SnS2 near 313cm-1 corresponds to the A1g vibration mode. It can be seen that after the SnS2/Bi2Se3 heterostructure is formed, three vibration modes exist, which are respectively positioned at 126cm < -1 >, 173cm < -1 > and 314cm < -1 >, and respectively correspond to the Eg and A1g vibration modes of Bi2Se3 and the A1g vibration mode of SnS2, so that the heterojunction can be shown to be SnS2/Bi2Se3 heterojunction (showing that the preparation of the SnS2/Bi2Se3 heterojunction is successful). When light is irradiated, the photocurrent density is obviously greater than that when the light is not irradiated; the photocurrent density at the light/dark cycle was still detected when no external bias was applied. The photoelectric detection can still be carried out under the condition of no external bias voltage, so that the photoelectric detection is further carried out under certain specific conditions (without an external power supply), and the photoelectric detection has better environmental adaptability and flexibility.

The performance characteristics of the high-efficiency PEC type photoelectric detector based on the SnS2/Bi2X3 heterojunction in the embodiment are as follows: FIG. 8 is a plot of photocurrent density as a function of light on/dark at-0.1V bias for a PEC-type photodetector based on a SnS2/Bi2X3 heterojunction made in accordance with the present invention; as shown in fig. 8, the abscissa in fig. 8 represents time, and the ordinate represents the magnitude of the photocurrent density. The graph shows the magnitude of the photocurrent density of different samples under alternating continuous bright and dark environments. Obviously, the photocurrent density in the illuminated (bright) environment is greater than the photocurrent density in the dark environment. In bright and dark environments, the difference in photocurrent density is the transient photocurrent density (Iph). The higher the transient photocurrent density (Iph), the better the photodetection performance, specifically, fig. 8 shows the transient photocurrent density (Iph) response curve measured at-0.1V bias voltage, alternating bright and dark environments, each duration of 5 s. The photocurrent density measured by the SnS2/Bi2Se3 heterojunction is the maximum and is about 21 times of SnS2 and 14 times of Bi2Se 3; the photocurrent density of the SnS2/Bi2Te3 heterojunction is about 14 times higher than that of SnS2 and about 12 times higher than that of Bi2Te 3; the method is obtained according to experimental data, and compared with pure SnS2, Bi2Se3 and Bi2Te3, the light current density and the light response of the SnS2/Bi2X3 heterojunction are improved by 14-20 times.

FIG. 9 is a bar graph of the photoresponse of a PEC-type photodetector based on a SnS2/Bi2X3 heterojunction made in accordance with the present invention at-0.1V bias; as shown in fig. 9, the abscissa in fig. 9 does not particularly denote, and the ordinate represents the magnitude of the light responsivity (Rph); according to a histogram of the light responsivity (Rph) calculated through the photocurrent density, the maximum light responsivity of the SnS2/Bi2Se3 heterojunction can be seen, and the light responsivity of the SnS2/Bi2Se3 heterojunction and the SnS2/Bi2Te3 heterojunction are greatly improved compared with that of SnS2 (tin sulfide), Bi2Se3 (bismuth selenide) and Bi2Te3 (bismuth telluride); in practical application, the optical detection performance can be quantitatively evaluated by using the photocurrent density (Iph) and the optical responsivity (Rph), and the calculation formula of the optical responsivity is as follows: the photocurrent density Iph is (Ilight-Idark)/S, where Ilight refers to the magnitude of the photocurrent in light, Idark refers to the magnitude of the photocurrent in a dark environment (no light), and S refers to the magnitude of the area of the heterojunction (working electrode) illuminated by light. The photoresponse Rph is the photocurrent density (Iph)/incident light power density.

Fig. 10 is a graph of photocurrent density as a function of light illumination/dark at a bias of 0V for a PEC-type photodetector based on the SnS2/Bi2X3 heterojunction manufactured according to the present invention, as shown in fig. 10, in which the abscissa represents time and the ordinate represents the magnitude of the photocurrent density. The graph shows the magnitude of the photocurrent density of two heterojunctions under 0V bias and alternating light and dark conditions. In bright and dark environments, the difference in photocurrent density is the transient photocurrent density (Iph). The higher the transient photocurrent density (Iph), the better the photoelectric detection performance; it can be seen that the detector still has an electro-optic response in the absence of an applied bias.

FIG. 11 is a graph of photocurrent density at different wavelengths (420nm, 450nm, 475nm, 500nm, 550nm, 600nm, and 650nm) for a PEC-type photodetector based on a SnS2/Bi2X3 heterojunction made in accordance with the present invention; as shown in fig. 11; the abscissa in fig. 11 represents time and the ordinate represents magnitude of photocurrent density, and from the photocurrent density of fig. 10, the photoresponsiveness of the PEC-type photodetector of the SnS2/Bi2X3 heterojunction under illumination of different wavelengths (420nm, 450nm, 475nm, 500nm, 550nm, 600nm and 650nm) can be calculated.

FIG. 12 is a graph of photocurrent density and photoresponse rate of SnS2/Bi2Se3 and SnS2/Bi2Te3 heterojunction of a heterojunction-based high-efficiency photodetector provided by an embodiment of the invention at different wavelengths; as shown in fig. 12; the abscissa in fig. 12 represents the wavelength of light and the ordinate (left) represents the transient photocurrent density (Iph), with a larger Iph indicating a better photodetection performance. The ordinate (right) represents the magnitude of the light responsivity (Rph), the larger Rph is, the better the photoelectric detection performance is; it can be seen from FIG. 12 that the detector has the maximum optical response under the illumination of 475nm wavelength, and can detect the light with a specific wavelength; compared with the II-type heterojunction SnS2/Bi2Te3, the I-type heterojunction SnS2/Bi2Se3 has higher transmission efficiency of electron-hole pairs and higher photoresponse due to lower transmission resistance with an electrolyte interface, namely the photoelectric property of the I-type heterojunction SnS2/Bi2Se3 is superior to that of the II-type heterojunction SnS2/Bi2Te3, because the charge transmission on the interface of the SnS2/Bi2Se3 heterojunction and the electrolyte is more effective; meanwhile, the PEC type photoelectric detector based on the SnS2/Bi2X3 heterostructure has different responses under different wavelengths of illumination, and can realize the detection and the differentiation of illumination in a specific wave band.

Optionally, since the material of the bismuth-series compound thin film may be bismuth telluride or bismuth selenide, if the material of the bismuth-series compound thin film is bismuth telluride, the process of preparing the heterojunction specifically includes:

the method comprises the following steps: placing a quartz tube on a furnace body, weighing 5mgBi2Te3 powder, placing the weighed Bi2Te3 powder at the center of a downstream temperature zone in the quartz tube, and then placing a substrate at a position which is 8cm away from the Bi2Te3 powder at the downstream of the quartz tube;

step two: mounting a flange to seal the quartz tube, forcibly pumping the pressure of the quartz tube to be less than 100Pa by using a vacuum pump, then opening an argon gas valve and continuously ventilating for 5 minutes at a flow rate of 200sccm to discharge residual air in the device, and then regulating the gas flow rate to be 25 sccm;

step three: setting the central temperature of the downstream temperature zone to be 20 minutes and increasing to 500 ℃, and maintaining for 4 minutes after the central temperature reaches the temperature;

step four: taking out the Bi2Te3 film after the temperature of the middle tube furnace in the step three is reduced to room temperature;

step five: placing a quartz tube on a furnace body, weighing 1g of SnCl 4.5H2O powder and 3g of sulfur powder, placing the weighed SnCl 4.5H2O powder at the center of a downstream temperature zone of the quartz tube, placing the weighed sulfur powder in the upstream direction 8cm away from the center of the upstream temperature zone in the quartz tube, and finally placing the prepared Bi2Te3 film as a substrate at the center of the downstream temperature zone by 10 cm;

step six: mounting a flange and sealing the quartz tube in the fifth step, forcibly pumping the pressure of the quartz tube to be below 100Pa by using a vacuum pump, then opening an argon gas valve and continuously ventilating for 5 minutes at a flow rate of 200sccm to discharge residual air in the device, and then regulating the gas flow rate to be 60 sccm;

step seven: setting the central temperature of an upstream temperature zone to be 300 ℃, the temperature rise time to be 30 minutes, setting the central temperature of a downstream temperature zone to be 10 minutes to 200 ℃, maintaining for 10 minutes, then raising the temperature to 450 ℃ for 10 minutes, and maintaining for 15 minutes after reaching the temperature;

step eight: and taking out the SnS2/Bi2Te3 van der Waals heterojunction after the temperature of the seven-tube furnace is reduced to the room temperature.

Or if the material of the bismuth-series compound thin film is bismuth selenide, the process for preparing the heterojunction specifically comprises the following steps:

the method comprises the following steps: placing a quartz tube on a furnace body, weighing 5mgBi2Se3 powder, placing the weighed Bi2Se3 powder at the center of a downstream temperature zone in the quartz tube, and then placing an ITO substrate at a position which is 8cm away from the Bi2Se3 powder at the downstream of the quartz tube;

step two: mounting a sealed quartz tube in the first step, forcibly pumping the quartz tube to be below 100Pa by using a vacuum pump, then opening an argon gas valve and continuously ventilating for 5 minutes to discharge residual air in the device, and then regulating the gas flow rate to 35 sccm;

step three: setting the central temperature of the downstream temperature zone to be 20 minutes and increasing to 500 ℃, and maintaining for 4 minutes after the central temperature reaches the temperature;

step four: taking out the Bi2Se3 film after the temperature of the middle-tube furnace in the step three is reduced to room temperature;

step five: placing a quartz tube on a furnace body, weighing 1g of SnCl 4.5H2O powder and 3g of sulfur powder, placing the weighed SnCl 4.5H2O powder at the center of a downstream temperature zone of the quartz tube, placing the weighed sulfur powder in the upstream direction 8cm away from the center of the upstream temperature zone in the quartz tube, and finally placing the prepared Bi2Se3 film as a substrate at the center of the downstream temperature zone by 10 cm;

step six: mounting a flange and sealing the quartz tube in the fifth step, forcibly pumping the pressure of the quartz tube to be below 100Pa by using a vacuum pump, then opening an argon gas valve and continuously ventilating for 5 minutes at a flow rate of 200sccm to discharge residual air in the device, and then regulating the gas flow rate to be 60 sccm;

step seven: setting the central temperature of an upstream temperature zone to be 300 ℃, the temperature rise time to be 30 minutes, setting the central temperature of a downstream temperature zone to be 10 minutes to 200 ℃, maintaining for 10 minutes, then raising the temperature to 450 ℃ for 10 minutes, and maintaining for 15 minutes after reaching the temperature;

step eight: and taking out the SnS2/Bi2Se3 van der Waals heterojunction after the temperature of the seven-tube furnace is reduced to the room temperature.

The application provides a preparation method of a heterojunction of a high-efficiency photoelectric detector based on the heterojunction, which comprises the following steps: disposing a bismuth-series compound and a substrate inside a quartz tube; heating a region corresponding to the bismuth series compound in the quartz tube to a preset first temperature, blowing argon to the position of a substrate from the direction of the bismuth series compound, and depositing on the substrate to obtain a bismuth series compound film;

SnCl4 & 5H2O and sulfur powder are sequentially arranged on one side of a substrate in a quartz tube;

heating the quartz tube to a preset second temperature, ventilating the bismuth-series compound substrate from the direction of sulfur powder by using argon gas, and depositing the surface of the bismuth-series compound film on the substrate to form a tin disulfide structure, namely, the heterojunction of the photoelectric detector prepared by the simple steps is used in the method, because the tin disulfide structure on the bismuth-series compound film in the heterojunction of the photoelectric detector is vertically arranged, the tin disulfide structure has a large specific surface area and forms a Van der Waals heterojunction with the bismuth-series compound film, and further when detecting optical signals, the separation and transmission of photon-generated carriers are accelerated, so that the photoelectric response of the photoelectric detector is improved.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.