Photoelectric absorption conversion layer, self-powered photoelectric detector and preparation method of self-powered photoelectric detector

Abstract

The invention provides a photoelectric absorption conversion layer, a self-powered photoelectric detector and a preparation method of the self-powered photoelectric detector, and belongs to the field of photoelectric detection. The photoelectric absorption conversion layer provided by the invention comprises three BixFeO3 film layers, x in each BixFeO3 film layer is more than or equal to 1 and less than 1.1, and the values of x in each BixFeO3 film layer are different. According to the self-powered photoelectric detector prepared by the photoelectric absorption conversion layer provided by the invention, the open-circuit voltage is 0.46-0.66 V and the short-circuit current is 1.13-1.6 * 10 <-4 > A / cm < 2 > under the illumination condition of 500 nm, and a zero-bias I-t curve shows that the self-powered photoelectric detector has a stable photoresponse phenomenon under the illumination condition of 500 nm; by adjusting the value of x in each BixFeO3 film layer, a photoelectric absorption conversion layer with different defect concentrations distributed in the longitudinal direction is designed, and then regulation and control over the light current density and the photo-generated voltage of the self-powered photoelectric detector are achieved.

Description

Technical Field

[0001] The invention relates to the field of photoelectric detection, and in particular to a photoelectric absorption conversion layer and a self-powered photoelectric detector and a preparation method thereof. Background Art

[0002] Photodetectors have broad application prospects in the fields of communications, environmental monitoring, missile detection, and astronomical research. Photodetectors can be divided into externally biased photodetectors and self-powered photodetectors. Externally biased photodetectors require external bias to be applied to the device as a driving force for the separation of photogenerated electrons and holes to obtain excellent detection performance. However, the addition of an external power source is not conducive to the miniaturization and integration of photodetection devices. Therefore, the research and development of self-powered photodetectors has gradually become the mainstream.

[0003] The main working mode of the self-powered photodetector is to separate photogenerated electrons and holes through the built-in electric field inside the device, so that it can generate significant photocurrent without external bias. Ferroelectric material films use the internal polarization electric field as the built-in electric field to drive the separation and transmission of photogenerated carriers, which can realize photoelectric detection and can be used as the photoelectric absorption and conversion layer in the self-powered photodetector. However, the internal depolarization field of the single-component ferroelectric material is too high, resulting in the instability of the internal polarization electric field of the ferroelectric material film, which is not conducive to the improvement and stability of the photoelectric performance. It is necessary to regularly maintain the stability of the internal polarization electric field through the method of external electric field polarization. This polarization step makes the application process of the device more cumbersome; and when the film formed by the composite of different ferroelectric materials is used as the photoelectric absorption and conversion layer in the self-powered photodetector, the diffusion between different ferroelectric materials will make the detection performance of the photodetector unstable. Summary of the invention

[0004] The purpose of the present invention is to provide a photoelectric absorption conversion layer and a self-powered photodetector and a preparation method thereof. The photoelectric absorption conversion layer provided by the present invention has high detection stability and light response when used in a self-powered photodetector.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a photoelectric absorption conversion layer, comprising three layers of Bi x FeO3 film, each layer of Bi x In the FeO3 film, 1≤x<1.1, and each layer of Bi x The value of x in the FeO3 film is different.

[0006] Preferably, each layer of Bi x The thickness of the FeO3 film is the same, both 75~100nm.

[0007] The present invention also provides a self-powered photoelectric detector, comprising a substrate, a bottom electrode, the photoelectric absorption conversion layer described in the above technical solution, and a top electrode which are arranged in sequence.

[0008] Preferably, the bottom electrode and the top electrode are both made of gold.

[0009] Preferably, the thickness of the bottom electrode and the top electrode is independently 30-50 nm.

[0010] The present invention also provides a method for preparing the self-powered photodetector described in the above technical solution, comprising the following steps: (1) sputtering a bottom electrode on a substrate to obtain a first composite; (2) preparing Bi on the bottom electrode surface of the first composite obtained in step (1) layer by layer x FeO3 film layer, the second composite is obtained; each layer of Bi x The preparation of FeO3 film includes spin coating Bi x FeO3 gel and annealing treatment; (3) sputtering a top electrode on the surface of the photoelectric absorption conversion layer of the second composite obtained in step (2) to obtain a self-powered photodetector.

[0011] Preferably, the temperature of each annealing treatment in step (2) is 600° C., and the time of each annealing treatment is 3 minutes.

[0012] Preferably, a thermal decomposition treatment is performed before each annealing treatment.

[0013] Preferably, the temperature of each thermal decomposition treatment is 320-380° C., and the time of each thermal decomposition treatment is 3-5 min.

[0014] Preferably, in step (1) and step (3), the sputtering power is independently 6-10 W, the sputtering time is independently 280-320 s, and the rotation speed of the turntable during sputtering is independently 14-16 r / min.

[0015] The present invention provides a photoelectric absorption conversion layer, comprising three layers of Bi x FeO3 film, each layer of Bi x In the FeO3 film, 1≤x<1.1, and each layer of Bi x The x value in the FeO3 film is different. x FeO3 film is used as photoelectric absorption conversion layer, Bi x FeO3 has room temperature multiferroicity and high remanent polarization strength (about 100µC / cm 2) and Curie temperature (about 830℃), a relatively low bandgap (<2.8eV), and at the same time, as a photoelectric absorption conversion layer, it has a single chemical composition, which can make the self-powered photodetector prepared by the photoelectric absorption conversion layer have stable detection performance and short response time; by adjusting the x value of each photoelectric absorption conversion layer, the longitudinal distribution of the internal defect concentration of the photoelectric absorption conversion layer is realized. The different distribution of the longitudinal defect concentration in the photoelectric absorption conversion layer can affect the longitudinal polarization electric field inside the film, thereby realizing the detection performance of the photodetector. The results of the embodiment show that the self-powered photodetector prepared by the photoelectric absorption conversion layer provided by the present invention has an open circuit voltage of 0.46~0.66V and a short circuit current of 1.13~1.6×10 -4 A / cm 2 , the zero bias It curve under 500nm illumination conditions shows that the self-powered photodetector has a stable photoresponse phenomenon.

[0016] In addition, the photoelectric absorption conversion layer provided by the present invention can be adjusted by adjusting each layer of Bi x By adjusting the value of x in the FeO3 film layer, a photoelectric absorption conversion layer with different longitudinal distributions of defect concentrations is designed, thereby realizing the regulation of the photocurrent and photovoltage of the self-powered photodetector. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a self-powered photodetector according to an embodiment of the present invention; Figure 2 The photovoltaic curves of the self-powered photodetector in Examples 1 to 3 of the present invention under dark and 500 nm illumination conditions; Figure 3 It is a zero bias voltage It curve diagram of the self-powered photodetector in Examples 1 to 3 of the present invention under 500nm illumination conditions; Figure 4 This is a photovoltaic curve diagram of the self-powered photodetector in Comparative Example 1 of the present invention under 500nm illumination conditions; Figure 5 This is a photovoltaic curve diagram of the self-powered photodetector in Comparative Example 2 of the present invention under 500nm illumination conditions; Figure 6 The photovoltaic curve diagram of the self-powered photodetector in comparative example 3 of the present invention under 500nm illumination and 365nm ultraviolet illumination. DETAILED DESCRIPTION

[0018] The present invention provides a photoelectric absorption conversion layer, comprising three layers of Bi x FeO3 film, each layer of Bi x In the FeO3 film, 1≤x<1.1, and each layer of Bi xThe value of x in the FeO3 film is different.

[0019] In the present invention, the Bi x The number of FeO3 film layers is 3. In the present invention, each layer of Bi x In the FeO3 film layer, 1≤x<1.1, preferably 1≤x<1.07; each layer of Bi x The value of x in the FeO3 film is different. In the embodiment of the present invention, the Bi x In the FeO3 film, x can be 1, 1.03 and 1.07. x The number of FeO3 film layers and the Bi x The value range of x in the FeO3 film is limited to the above range and each layer of Bi x Different values ​​of x in the FeO3 film layer can ensure that there is a longitudinal defect concentration difference inside the photoelectric absorption conversion layer, further improving the photoelectric detection performance of the self-powered photodetector.

[0020] In the present invention, the thickness of each photoelectric absorption conversion layer is preferably the same, 75 to 100 nm, more preferably 75 to 90 nm, and further preferably 75 to 80 nm. The present invention limits the thickness of each photoelectric absorption conversion layer to the above range so that the photoelectric absorption conversion layer as a whole has a suitable thickness and is conducive to the regulation of defects in the photoelectric absorption conversion layer.

[0021] The present invention adopts multi-layer Bi x FeO3 film is used as photoelectric absorption conversion layer, Bi x FeO3 has room temperature multiferroicity and high remanent polarization strength (about 100µC / cm 2 ) and Curie temperature (about 830℃), and a relatively low bandgap (<2.8eV). At the same time, as a photoelectric absorption conversion layer, it has a single chemical composition, which can make the self-powered photodetector prepared by the photoelectric absorption conversion layer have stable detection performance and short response time. By adjusting the x value of each photoelectric absorption conversion layer, the longitudinal distribution of the defect concentration inside the photoelectric absorption conversion layer can be achieved. The different distributions of the longitudinal defect concentration in the photoelectric absorption conversion layer can change the state of the polarization electric field inside the film, thereby realizing the regulation of the detection performance of the photodetector.

[0022] The present invention also provides a self-powered photoelectric detector, comprising a substrate, a bottom electrode, the photoelectric absorption conversion layer described in the above technical solution, and a top electrode which are arranged in sequence.

[0023] The self-powered photodetector provided by the present invention comprises a substrate. As an embodiment of the present invention, the substrate may be a Si / SiO2 substrate.

[0024] The self-powered photoelectric detector provided by the present invention further comprises a bottom electrode arranged on the surface of the substrate.

[0025] As an embodiment of the present invention, when the substrate is a Si / SiO 2 substrate, the bottom electrode is disposed on the SiO 2 surface of the substrate.

[0026] In the present invention, the material of the bottom electrode is preferably gold; the thickness of the bottom electrode is preferably 30-50 nm, more preferably 40-50 nm, and further preferably 50 nm. The present invention limits the material and thickness of the bottom electrode to the above range so that the bottom electrode layer can maintain good conductivity and light transmittance.

[0027] The self-powered photoelectric detector provided by the present invention further comprises a photoelectric absorption conversion layer arranged on the surface of the bottom electrode. The photoelectric absorption conversion layer is the photoelectric absorption conversion layer described in the above technical solution.

[0028] The self-powered photoelectric detector provided by the present invention further comprises a top electrode arranged on the surface of the photoelectric absorption conversion layer.

[0029] In the present invention, the material of the top electrode is preferably gold; the thickness of the top electrode is preferably 30-50 nm, more preferably 40-50 nm, and further preferably 50 nm. The present invention limits the material and thickness of the top electrode to the above range so that the top electrode layer can maintain good conductivity and light transmittance.

[0030] In the present invention, the top electrode does not completely cover the photoelectric absorption conversion layer. In the present invention, the top electrode does not completely cover the photoelectric absorption conversion layer to promote the photoelectric absorption conversion layer to use light, ensuring that the self-powered photodetector has good photoelectric detection performance.

[0031] As an embodiment of the present invention, the top electrode may be a dot-shaped electrode with a diameter of 200 μm.

[0032] The present invention also provides a method for preparing the self-powered photodetector described in the above technical solution, comprising the following steps: (1) sputtering a bottom electrode on a substrate to obtain a first composite; (2) preparing Bi on the bottom electrode surface of the first composite obtained in step (1) layer by layer x FeO3 film layer, the second composite is obtained; each layer of Bi x The preparation of FeO3 film includes spin coating Bi x FeO3 gel and annealing treatment; (3) sputtering a top electrode on the surface of the photoelectric absorption conversion layer of the second composite obtained in step (2) to obtain a self-powered photodetector.

[0033] The present invention sputters a bottom electrode on a substrate to obtain a first composite body.

[0034] In the present invention, the substrate is preferably pretreated before use; the pretreatment is preferably ultrasonic cleaning; the cleaning solution used for the ultrasonic cleaning is preferably dilute hydrochloric acid, acetone, deionized water and anhydrous ethanol in sequence. The present invention has no special requirements for the concentration of the dilute hydrochloric acid, and the concentration of dilute hydrochloric acid commonly used by those skilled in the art in ultrasonic cleaning can be used. The present invention has no special restrictions on the frequency and time of the ultrasonic cleaning, and the frequency and time of ultrasonic cleaning commonly used by those skilled in the art can be used.

[0035] As an embodiment of the present invention, when the cleaning liquid used for the ultrasonic cleaning is dilute hydrochloric acid, the time of the ultrasonic cleaning can be 2 minutes; when the cleaning liquid used for the ultrasonic cleaning is acetone, deionized water or anhydrous ethanol, the time of the ultrasonic cleaning can be 8 minutes.

[0036] After the ultrasonic cleaning is completed, the present invention preferably further wipes and dries the ultrasonically cleaned substrate to obtain a pretreated substrate.

[0037] In the present invention, the wiping is preferably wiping with lens cleaning paper.

[0038] As an embodiment of the present invention, the drying may be performed on a flat furnace; the drying temperature may be 150° C.; and the drying time may be 5 minutes.

[0039] After drying is completed, the present invention preferably air-cools the dried substrate to room temperature.

[0040] In the present invention, the sputtering of the bottom electrode is preferably carried out in a magnetron sputtering apparatus; the power of the sputtering is preferably 6-10W, more preferably 8W; the time of the sputtering is preferably 280-320s, more preferably 300s; the rotation speed of the turntable during the sputtering is preferably 14-16r / min, more preferably 15r / min. The present invention sets the sputtering parameters of the bottom electrode within the above range to ensure uniform sputtering of the bottom electrode and the top electrode, improve the quality of the bottom electrode layer and the top electrode layer, and further improve the photoelectric detection performance of the self-powered photodetector.

[0041] After obtaining the first composite, the present invention prepares Bi layer by layer on the bottom electrode surface of the first composite. x FeO3 film layer to obtain the second composite.

[0042] In the present invention, each layer of Bi x The preparation of FeO3 film includes spin coating Bi x FeO3 gel and annealing treatment.

[0043] The present invention is to x The preparation method of FeO3 gel is not particularly limited, and Bi is prepared by a sol-gel method commonly used by those skilled in the art. x FeO3 gel will do.

[0044] The present invention has no special limitation on the spin coating operation. The spin coating operation is performed by a method known to those skilled in the art. x The thickness of FeO3 gel after annealing treatment can be 75~100nm.

[0045] In the present invention, it is preferred to perform a thermal decomposition treatment before each annealing treatment.

[0046] As an embodiment of the present invention, the temperature of each thermal decomposition treatment can be 320-380°C, or 350°C; the time of each thermal decomposition treatment can be 3-5 minutes, or 4 minutes. The present invention limits the temperature and time of each thermal decomposition treatment to the above range to remove Bi x Organic solvent inside the film formed by spin coating of FeO3 gel.

[0047] In the present invention, the temperature of each annealing treatment is preferably 580-620°C, more preferably 600°C; the time of each annealing treatment is preferably 2-4 minutes, more preferably 3 minutes. The present invention sets the temperature and time of each annealing treatment to the above ranges so that Bi x FeO3 gel crystallization, obtain crystalline Bi x FeO3 film layer (photoelectric absorption conversion layer).

[0048] After each annealing treatment is completed, the present invention preferably air cools the annealed composite to room temperature.

[0049] After obtaining the second composite, the present invention sputters a top electrode on the upper surface of the second composite to obtain a self-powered photodetector.

[0050] In the present invention, the parameter setting range and preferred values ​​of the sputtering top electrode are the same as the parameter setting range and preferred values ​​of the sputtering bottom electrode, and will not be described in detail here.

[0051] As an embodiment of the present invention, the top electrode may be covered with a mask having an aperture of 200 μm on the photoelectric absorption conversion layer before sputtering, and then sputtering is performed to obtain a dot-shaped electrode with a diameter of 200 μm.

[0052] In a specific embodiment of the present invention, the structural schematic diagram of the self-powered photodetector is as follows: Figure 1 As shown: from Figure 1It can be seen that the self-powered photodetector includes a Si / SiO2 substrate, a bottom electrode, a first photoelectric absorption conversion layer, a second photoelectric absorption conversion layer, a third photoelectric absorption conversion layer and a top electrode which are arranged in sequence.

[0053] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] Example 1 A photoelectric absorption conversion layer, comprising three layers of Bi x FeO3 film layer composition, specifically, BiFeO3 film layer, Bi 1.03 FeO3 film and Bi 1.07 FeO3 film, each layer of Bi x The thickness of the FeO3 film is 75nm.

[0055] Example 2 A photoelectric absorption conversion layer, comprising three layers of Bi x FeO3 film composition, specifically Bi 1.07 FeO3 film, Bi 1.03 FeO3 film and BiFeO3 film, each layer of Bi x The thickness of the FeO3 film is 75nm.

[0056] Example 3 A photoelectric absorption conversion layer, comprising three layers of Bi x FeO3 film composition, specifically Bi 1.03 FeO3 film, BiFeO3 film and Bi 1.07 FeO3 film, each layer of Bi x The thickness of the FeO3 film is 75nm.

[0057] Comparative Example 1 A photoelectric absorption conversion layer is a BiFeO3 film layer with a thickness of 225nm.

[0058] Comparative Example 2 A photoelectric absorption conversion layer, Bi 1.1 FeO3 film layer, thickness is 225nm.

[0059] Comparative Example 3 A photoelectric absorption conversion layer is composed of a BiFeO3 film layer and a BaTiO3 film layer which are arranged in sequence. The thickness of the BiFeO3 film layer is 190nm, and the thickness of the BaTiO3 film layer is 35nm.

[0060] Application Example 1 A self-powered photodetector, comprising a Si / SiO2 substrate, a bottom electrode, the photoelectric absorption conversion layer in Example 1 and a top electrode arranged in sequence; the BiFeO3 film layer of the photoelectric absorption conversion layer in Example 1 is in contact with the bottom electrode; the bottom electrode and the top electrode are both made of gold; the bottom electrode is 50 nm thick; the top electrode is a dot-shaped electrode with a diameter of 200 μm and a thickness of 50 nm; The preparation method of the self-powered photodetector is as follows: (1) The Si / SiO2 substrate was first placed in dilute hydrochloric acid for ultrasonic cleaning for 2 minutes, and then placed in acetone, deionized water and anhydrous ethanol for ultrasonic cleaning for 8 minutes respectively, and then wiped clean with lens cleaning paper after being taken out, and finally placed on a flat furnace for drying at 150°C for 5 minutes and then air-cooled to room temperature to obtain a pretreated substrate, and the pretreated substrate was fixed on a turntable, and sputtered for 300 seconds at a sputtering power of 8 W in a magnetron sputtering instrument to prepare a bottom electrode to obtain a first composite; the rotation speed of the turntable during the sputtering was 15 r / min; (2) Spin-coat three layers of Bi on the bottom electrode surface of the first composite obtained in step (1) layer by layer x FeO3 gel, the first layer is spin-coated BiFeO3 gel, the second layer is spin-coated Bi 1.03 FeO3 gel, the third layer is spin-coated Bi 1.07 After each spin coating, the FeO3 gel was first subjected to a thermal decomposition treatment at 350°C for 5 min and then annealed at 600°C for 3 min to obtain a second composite; (3) The second composite obtained in step (2) is fixed on a turntable, and a mask with an aperture of 200 μm is covered on the surface of the photoelectric absorption conversion layer of the second composite in a magnetron sputtering apparatus and sputtered at a sputtering power of 8 W for 300 s to prepare a top electrode, thereby obtaining a self-powered photodetector; the rotation speed of the turntable during the sputtering is 15 r / min.

[0061] Application Example 2 The difference between Application Example 2 and Application Example 1 is that the photoelectric absorption conversion layer in Example 2 is used. 1.07 The FeO3 film layer is in contact with the bottom electrode, and in step (2) of the preparation method, three layers of Bi with corresponding components are spin-coated. x FeO3 gel, other parts are the same as those in Application Example 1.

[0062] Application Example 3 The difference between Application Example 3 and Application Example 1 is that the photoelectric absorption conversion layer in Example 3 is used. 1.03 The FeO3 film layer is in contact with the bottom electrode, and in step (2) of the preparation method, three layers of Bi with corresponding components are spin-coated. x FeO3 gel, other parts are the same as those in Application Example 1.

[0063] Comparative application example 1 The difference between Comparative Application Example 1 and Application Example 1 is that the photoelectric absorption conversion layer in Comparative Example 1 is used, and a layer of BiFeO3 gel with corresponding composition and thickness is spin-coated in step (2) of the preparation method, and the rest is the same as Application Example 1.

[0064] Comparative Application Example 2 The difference between Comparative Example 2 and Example 1 is that the photoelectric absorption conversion layer in Comparative Example 2 is used, and a layer of Bi with a corresponding composition and thickness is spin-coated in step (2) of the preparation method. 1.1 FeO3 gel, other parts are the same as those in Application Example 1.

[0065] Comparative Application Example 3 The difference between Comparative Application Example 3 and Application Example 1 is that the photoelectric absorption conversion layer in Comparative Example 3 is used, the BiFeO3 film layer of the photoelectric absorption conversion layer in Comparative Example 3 is in contact with the bottom electrode, two layers of gel of corresponding composition and thickness are spin-coated in step (2) of the preparation method, the annealing temperature of the BaTiO3 film layer is 650°C, and the rest is the same as in Application Example 1.

[0066] The electrical performance test of the self-powered photodetector in the corresponding application examples 1 to 3 and the comparative application examples 1 to 3 was performed using a semiconductor device analyzer. The light source was provided by a single-wavelength LED lamp, and the wavelength of the light source was 500 nm and 365 nm.

[0067] The photovoltaic curves of the self-powered photodetectors in Application Examples 1, 2 and 3 under dark and 500nm illumination conditions are shown in FIG. Figure 2 As shown, from Figure 2 It can be seen that the horizontal axis and the vertical axis are voltage and current density, respectively. The open circuit voltage and short circuit current of the self-powered photodetector in Application Example 1 are 0.46 V and 1.18×10 -4 A / cm 2 The open circuit voltage and short circuit current of the self-powered photodetector in Application Example 2 are 0.66 V and 1.6 × 10 -4 A / cm 2 The open circuit voltage and short circuit current of the self-powered photodetector in Application Example 3 are 0.6 V and 1.13 × 10 -4 A / cm 2, Application Examples 1~3 all show a certain intensity of photocurrent density under the condition of zero voltage, indicating that there is a stable built-in electric field for separating photogenerated carriers in the two devices, but the photovoltaic effects of Application Examples 1~3 are different, indicating that by adjusting the composition of each layer in the photoelectric absorption conversion layer, the distribution of defects inside the device can be controlled, which is helpful to regulate the detection performance of the self-powered photodetector.

[0068] The zero bias It curves of the self-powered photodetectors in Application Examples 1, 2 and 3 under 500nm illumination are shown in FIG. Figure 3 As shown, from Figure 3 It can be seen that the horizontal and vertical axes are time and current density, respectively, and the switching interval is 10s. The self-powered photodetectors in application examples 1 to 3 all have stable photoresponse phenomena, but the photocurrent density (detection performance) is different, indicating that the photoresponse behavior of the device can be regulated by controlling the distribution of internal defects of the device, thereby regulating the detection performance of the self-powered photodetector.

[0069] The photovoltaic curve of the self-powered photodetector in Application Example 1 under 500nm illumination is shown in Figure 2. Figure 4 As shown, from Figure 4 It can be seen that the horizontal axis and the vertical axis are voltage and current density, respectively. In contrast, the open circuit voltage and short circuit current of the self-powered photodetector in Application Example 1 are 0.35 V and 2.9×10 -5 A / cm 2 Since BiFeO3 gel is used in the preparation of the photoelectric absorption conversion layer, the volatilization of Bi element during the annealing process of the photoelectric absorption conversion layer leads to a large number of defects inside the film, which in turn forms too many defects and becomes the carrier recombination center, resulting in a decrease in photocurrent, which is not conducive to the improvement of photoelectric detection performance.

[0070] The photovoltaic curve of the self-powered photodetector in Application Example 2 under 500nm illumination is as follows: Figure 5 As shown, from Figure 5 It can be seen that the horizontal axis and the vertical axis are voltage and current density, respectively. In contrast, the open circuit voltage and short circuit current of the self-powered photodetector in Application Example 2 are 0.4 V and 6.8×10 -5 A / cm 2 Since the photoelectric absorption conversion layer is made of Bi 1.1 FeO3 gel, Bi element excess reaches 10%, resulting in too many defects inside the film, which is not conducive to the increase of current value (improvement of photoelectric detection performance); and the composition is single (all Bi 1.1 FeO3), which is not conducive to the regulation of the built-in electric field of the film and the performance of the detection device.

[0071] Comparative Application Example 3 shows the photovoltaic curves of the self-powered photodetector under 500nm illumination and 365nm ultraviolet illumination. Figure 6 As shown, from Figure 6 It can be seen that the horizontal axis and the vertical axis are voltage and current density, respectively. In contrast, the open circuit voltage and short circuit current of the self-powered photodetector in Application Example 3 under 500nm illumination are 0.35V and 4.9×10 -6 A / cm 2 , the open circuit voltage and short circuit current under 365nm UV light are 0.63V and 3.35×10 -5 A / cm 2 , the response wavelength of the self-powered photodetector is in the ultraviolet light band, and the response is weak in the visible light band.

[0072] The self-powered photodetector prepared by the photoelectric absorption conversion layer provided by the present invention has an open circuit voltage of 0.46~0.66V and a short circuit current of 1.13~1.6×10 -4 A / cm 2 , the zero bias It curve under 500nm illumination condition shows that the self-powered photodetector has a stable light response phenomenon. In addition, the photoelectric absorption conversion layer provided by the present invention can be adjusted by adjusting each layer of Bi x By adjusting the value of x in the FeO3 film layer, a photoelectric absorption conversion layer with different longitudinal distributions of defect concentrations is designed, thereby achieving regulation of the photocurrent and photovoltage performance of the self-powered photodetector.

[0073] 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 principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A photoelectric absorption conversion layer, characterized in that: Including 3 layers of Bi x FeO3 film, each layer of Bi x In the FeO3 film, 1≤x<1.1, and each layer of Bi x The value of x in the FeO3 film is different.

2. The photoelectric absorption conversion layer according to claim 1, characterized in that: Each layer of Bi x The thickness of the FeO3 film is the same, both 75~100nm.

3. A self-powered photodetector, comprising a substrate, a bottom electrode, the photoelectric absorption conversion layer according to claim 1 or 2, and a top electrode arranged in sequence.

4. The self-powered photodetector according to claim 3, characterized in that: The bottom electrode and the top electrode are both made of gold.

5. The self-powered photodetector according to claim 3 or 4, characterized in that: The thickness of the bottom electrode and the top electrode is independently 30-50 nm.

6. The method for preparing the self-powered photodetector according to any one of claims 3 to 5, comprising the following steps: (1) sputtering a bottom electrode on a substrate to obtain a first composite; (2) preparing Bi on the bottom electrode surface of the first composite obtained in step (1) layer by layer x FeO3 film layer, the second composite is obtained; each layer of Bi x The preparation of FeO3 film includes spin coating Bi x FeO3 gel and annealing treatment; (3) sputtering a top electrode on the surface of the photoelectric absorption conversion layer of the second composite obtained in step (2) to obtain a self-powered photodetector.

7. The preparation method according to claim 6, characterized in that: The temperature of each annealing treatment in step (2) is 600° C., and the time of each annealing treatment is 3 minutes.

8. The preparation method according to claim 6 or 7, characterized in that: A thermal decomposition treatment is performed before each annealing treatment.

9. The preparation method according to claim 8, characterized in that: The temperature of each thermal decomposition treatment is 320-380° C., and the time of each thermal decomposition treatment is 3-5 min.

10. The preparation method according to claim 6, characterized in that: In the step (1) and the step (3), the sputtering power is independently 6-10 W, the sputtering time is independently 280-320 s, and the rotation speed of the turntable during the sputtering is independently 14-16 r / min.

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