A method for constructing a self-powered photoelectrochemical (PEC) photodetector with bias-driven photocurrent polarity conversion (PPC) behavior

Abstract

The present invention provides a method for fabricating a novel self-powered photoelectrochemical photodetector with bias-driven PPC behavior, which utilizes the phenomenon of photocurrent polarity conversion (PPC). According to the characteristics of the s-type heterostructure, the Bi2O2S nanosheets are combined with the conductive polymer polyaniline (PANI) to form an organic-inorganic hybrid structure, successfully constructing a high-performance self-powered photoelectrochemical (PEC) photodetector with bias-driven PPC behavior. The electron transfer mechanism predicted by density functional theory (DFT) shows that the present invention conforms to the s-type heterostructure. Benefiting from this structure, the dark current density of the device is reduced by more than 20 times. In addition, the self-powered device exhibits PPC when tested at 0 V bias, and the negative photocurrent responsivity at 350 nm can reach -30 mA / W. This can already be comparable to commercially leading self-powered electronic products (the negative photocurrent responsivity at 365 nm is -31 mA / W). Overall, this study is significantly more versatile in performance than traditional detectors, has a wider application range, and has a simple manufacturing process and low cost, making it suitable for large-scale preparation, opening up a promising path for future research in the optoelectronic field.

Description

Technical Field

[0001] The present invention belongs to the field of photoelectrochemical detection, and particularly relates to a method for constructing a self-powered photoelectrochemical (PEC) photodetector with a bias-driven photocurrent polarity conversion (PPC) behavior Background Art

[0002] Electronic components such as modulators, couplers, photodiodes, sensors, and photodetectors are usually used in many electronic devices (such as photovoltaic cells, transistors, etc.) attached to semiconductor heterostructures. These devices play an indispensable role in the device and require superior materials to meet their requirements for device performance. A series of two-dimensional semiconductor materials represented by graphene have been widely explored by many scholars because the physical property regulation of two-dimensional materials may provide a general method to solve the technical challenges of electronic devices faced by the development of science and technology. Various methods such as traditional transition metal dichalcogenides (TMDCs), black phosphorus (BP), and carbon nanotubes have been introduced to establish high-performance optoelectronic devices, but the effects are not ideal. Currently, semiconductor materials based on p-n junctions, as a sensor that can convert optical signals into electrical signals that can be received and processed, have superior device performance and have achieved remarkable application results, and are widely used in the fields of electronics, optoelectronics, and other electronics. However, traditional p-n junctions have many limitations such as poor biocompatibility, short lifespan, and high cost. For example, currently, optoelectronic devices based on traditional two-dimensional p-n junctions are widely used in solid-state electronic devices. This device has high performance, but its optical response tends to be single, which severely restricts its development

[0003] The rapid development of optical communication and integrated circuit technology has forced us to develop new general strategies suitable for modern society to solve the technical barriers in the electronic field. Impressively, the emergence of the photocurrent polarity conversion (PPC) phenomenon provides new possibilities for the development of future optoelectronic technologies. The present invention combines Bi2O2S nanosheets with a conductive polymer polyaniline (PANI) organic-inorganic hybrid structure to construct a self-powered photoelectrochemical (PEC) photodetector with a bias-driven PPC behavior. At the same time, the density functional theory (DFT) is used to predict the electron transfer mechanism, indicating that it conforms to the s-type heterostructure. Thanks to this structure, the dark current density of the device is reduced by more than 20 times. In addition, the self-powered device exhibits PPC at 0 V bias, which is due to the redox reaction triggered between the hybrid structure and the electrolyte interface in the device. At 0 V bias, the negative optical responsivity at 350 nm can reach -30 mA / W. This can already be comparable to commercially leading self-powered electronic products (whose negative optical responsivity at 365 nm is -31 mA / W). Generally speaking, this research has opened up a promising path for future research in the field of optoelectronics Summary of the Invention

[0004] To overcome the defects of the above-mentioned prior art, the object of the present invention is to provide a method for constructing a self-powered photoelectrochemical (PEC) photodetector with a biased-driven PPC behavior.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] 1) 100 mg of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) and 20 mL of deionized water are poured into a 50 mL volumetric beaker A. The beaker A is placed under ultrasonic treatment to make the internal mixture more uniform until it is completely dissolved. The beaker A is left standing for a period of time to ensure that no precipitation occurs.

[0007] 2) 1 mL of hydrazine hydrate (N2H4·H2O) and 12.7 mg of thiourea are mixed and placed in beaker B, and ultrasonic treatment is carried out for 2 h to fully mix the materials.

[0008] 3) Take the solution in beaker A obtained in step 1), mix it with the solution in beaker B obtained in step 2), add 120 mg of potassium hydroxide and 320 mg of sodium hydroxide, continuously stir for 30 minutes, and leave it standing overnight. Then collect the dark precipitate, wash it 3 times with deionized water and alcohol respectively. Finally, dry it in a vacuum drying oven at 70 °C for 12 h to collect the pure bismuth oxysulfide (Bi2O2S) nanosheet powder.

[0009] 4) Weigh a certain amount of PANI and the Bi2O2S nanosheets obtained in step 3), continue ultrasonic treatment at room temperature for several hours, centrifuge to collect the obtained pure hybrid structure product, and then dry it for 12 h.

[0010] 5) Take 1 mg of the hybrid structure sample obtained in step 4) and add it to 1 mL of NMP solution to prepare a 1 mg / mL solution, and use ultrasonic treatment until the solution is uniformly mixed.

[0011] 6) Spin-coat the solution sample obtained in step 6) on the surface of a conductive ITO (1 cm * 2 cm) at a constant speed, with a spin-coating area of (1 cm * 1 cm), and then place it in an oven and leave it standing for 24 h. After drying, leave the device standing under ambient conditions for several hours.

[0012] 7) Perform photoelectric performance tests on the photodetector obtained in step 6). The test system uses a three-electrode system electrochemical workstation (CHI660D, Chenhua, China) with a working electrode, a counter electrode (Pt), and a reference electrode (saturated calomel electrode).

[0013] 8) Repeat the experiment by changing the parameters in the flexible optoelectronic detector voltage test in step 7). The changed parameters are that the electrolyte solution during the test is a KOH solution with a concentration of 0.2 mol / L - 0.5 mol / L. The light source is a xenon lamp (300 - 780 nm), and the light intensity is 40 - 60 mW / cm 2 , and external light of different wavelengths is tested using filters of different wavelengths.

[0014] 9) Conduct a cyclic test on the sample for 4000 s under the parameters set in step 8),

[0015] Preferably according to the present invention, in step 1), the ultrasonic treatment time is 2 h.

[0016] Preferably according to the present invention, in step 2), the mass of thiourea is 12.7 mg, and the volume of hydrazine hydrate is 1 mL.

[0017] Preferably according to the present invention, in step 3), the vacuum drying treatment time is 12 h, and the temperature is 70 °C.

[0018] Preferably according to the present invention, in step 4), the mass of the bismuth oxy-sulfide sample used is 2 mg, the volume of PANI is 2 mL, the ultrasonic time is 2 h, the number of centrifugation treatments is three times, and the drying treatment time is 12 h.

[0019] Preferably according to the present invention, in step 5), the mass of the hybrid structure sample is 1 mg, the volume of the NMP solution is 1 mL, and the ultrasonic treatment time is 2 h.

[0020] Preferably according to the present invention, in step 6), the volume of the spin-coated hybrid structure solution is 0.2 mL, the concentration is 1 mg / mL, the oven drying temperature is 60 °C, the drying time is 24 h, and the standing time at room temperature is 4 h.

[0021] Preferably according to the present invention, in step 7), the electrochemical workstation used in the electrochemical test is an electrochemical workstation with a three-electrode system.

[0022] Preferably according to the present invention, in step 8), the KOH solution used as the electrolyte solution during the test is tested at concentrations of 0.2, 0.3, 0.4, and 0.5 mol / L respectively. The phenomenon is the best when the concentration is 0.5 mol / L. The wavelengths of the filters used are 350 nm, 365 nm, 546 nm, 630 nm, 660 nm, 700 nm, and 760 nm for testing, and the selected light intensities during the test are 40, 45, 50, 55, and 60 mW / cm 2 .

[0023] All the devices and raw materials in the method of the present invention are commercially available products. Based on the above technical solutions, the present invention has the following advantages:

[0024] (1) Through research, it is found that the self-powered photoelectrochemical (PEC) photodetector with bias-driven photocurrent polarity conversion (PPC) behavior exhibits a brand-new PPC regulation characteristic, excellent stability and durability.

[0025] (2) It is found through research that this self-powered photoelectrochemical (PEC) photodetector with bias-driven PPC behavior is significantly superior in performance to traditional detectors, has a wider application range, and has a simple manufacturing process and low cost, and can be used for large-scale preparation.

[0026] (3) The present invention provides a new technical route for future electronics, optoelectronics and even other electronics fields, and opens up a promising path for the research in the future optoelectronics field. Description of the Drawings

[0027] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art:

[0028] Figure 1 It is a schematic diagram of the preparation method of the Bi2O2S / PANI hybrid structure nanosheet electrode in Example 1 of the present invention.

[0029] Figure 2 It is a schematic Raman spectrum diagram of the hybrid structure containing different masses of PANI manufactured in Example 1 of the present invention.

[0030] Figure 3 It is the FTIR spectrum of the hybrid structure containing different masses of PANI manufactured in Example 1 of the present invention.

[0031] Figure 4 It is a schematic structural diagram of the PEC photodetector manufactured in Example 1 of the present invention.

[0032] Figure 5 It is a repeated switching photocurrent-time characteristic curve diagram of the PEC photodetector prepared by comparing the hybrid structure manufactured in Example 1 with the single two-dimensional Bi2O2S nanosheet manufactured in Example 2.

[0033] Figure 6 It is a photocurrent density-time characteristic curve diagram of the hybrid structure nanosheet prepared in Example 1 of the present invention tested under different positive bias voltages, and its photocurrent density exhibits PPC behavior at 0 V.

[0034] Figure 7It is a schematic diagram of photocurrent density - time tested under different light irradiances at 0V for the present invention. (40, 45, 50, 55, 60 mW / cm 2 )

[0035] Figure 8 It is a schematic diagram of photocurrent density tested under different concentrations of KOH electrolyte solutions at 0V for the present invention. (0.2, 0.3, 0.4, 0.5 mol / L)

[0036] Figure 9 It is a schematic diagram of impedance (EIS) tested under different concentrations of KOH electrolyte solutions at 0V for the present invention. (0.2, 0.3, 0.4, 0.5 mol / L)

[0037] Figure 10 It is a photocurrent density - time characteristic curve graph for testing the response time and relaxation time of the present invention at 0V.

[0038] Figure 11 It is a photocurrent density - time characteristic curve graph for testing the response time and relaxation time of the present invention under different concentrations of KOH electrolyte solutions at 0V. (0.2, 0.3, 0.4, 0.5 mol / L)

[0039] Figure 12 It is a responsivity - photocurrent density characteristic curve graph for testing the photocurrent density and responsivity of the present invention under different wavelengths of filter at 0V. (350, 365, 546, 630, 660, 700, 760 nm)

[0040] Figure 13 It is a schematic diagram of photocurrent density - time characteristic for testing the photocurrent density of the present invention under different bias voltages at a wavelength of 350 nm.

[0041] Figure 14 It is a schematic diagram of photocurrent density - time characteristic obtained by testing the durability and stability of the present invention. Detailed implementation manners

[0042] Example 1

[0043] A method for constructing a self - powered photoelectrochemical (PEC) photodetector with bias - driven photocurrent polarity conversion (PPC) behavior, wherein the flexible photodetector is a photoelectrochemical photodetector using deionized water solid electrolyte as the conductive medium, and the method includes the following steps:

[0044] 1) 100 mg of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) and 20 mL of deionized water were poured into a 50 mL volumetric beaker A. The beaker A was placed under ultrasonic treatment to make the internal mixture more uniform until it was completely dissolved. The beaker A was left standing for a period of time to ensure that no precipitation occurred.

[0045] 2) 1 mL of hydrazine hydrate (N2H4·H2O) and 12.7 mg of thiourea were mixed and placed in beaker B, and ultrasonic treatment was carried out for 2 h to fully mix the materials.

[0046] 3) Take the solution in beaker A obtained in step 1) and mix it with the solution in beaker B obtained in step 2). Add 120 mg of potassium hydroxide and 320 mg of sodium hydroxide and continuously stir for 30 minutes, then let it stand overnight. After that, collect the dark precipitate, wash it 3 times with deionized water and alcohol respectively. Finally, dry it in a vacuum drying oven at 70 °C for 12 h to collect pure bismuth oxysulfide (Bi2O2S) nanosheet powder.

[0047] 4) Weigh a certain amount of PANI and the Bi2O2S nanosheets obtained in step 3), continue ultrasonic treatment at room temperature for several hours, centrifuge to collect the obtained pure hybrid structure product, and then dry it for 12 h.

[0048] 5) Take 1 mg of the hybrid structure sample obtained in step 4) and add it to 1 mL of NMP solution to prepare a 1 mg / mL solution, and use ultrasonic treatment until the solution is evenly mixed.

[0049] 6) The solution sample obtained in step 5) was spin-coated on the surface of a conductive ITO (1 cm * 2 cm) at a constant speed, and the spin-coated area was (1 cm * 1 cm), and then placed in an oven and left standing for 24 h. After drying, the device was left standing under ambient conditions for several hours.

[0050] 7) The optoelectronic properties of the photodetector obtained in step 6) were tested. The test system used a three-electrode system electrochemical workstation (CHI660D, Chenhua, China) with a working electrode, a counter electrode (Pt), and a reference electrode (saturated calomel electrode).

[0051] 8) Repeat the experiment by changing the parameters for the voltage test of the flexible photodetector in step 7). The light source was a xenon lamp (300 - 780 nm), the changed parameter was the applied bias voltage of different magnitudes. When testing, the electrolyte solution was a KOH solution in the concentration range of 0.2 mol / L - 0.5 mol / L, and the light intensity was 40 - 60 mW / cm 2 , and use filter films of different wavelengths to test the photocurrent density at different wavelengths.

[0052] Figure 1Schematic diagram of the preparation method of the Bi2O2S / PANI hybrid structure nanosheet electrode in Example 1 of the present invention.

[0053] Figure 2 Schematic Raman spectrum of the hybrid structure containing different masses of PANI fabricated in Example 1 of the present invention.

[0054] Figure 3 FTIR spectrum of the hybrid structure containing different masses of PANI fabricated in Example 1 of the present invention.

[0055] Figure 4 Schematic diagram of the structure principle of the PEC photodetector fabricated in Example 1 of the present invention.

[0056] Figure 5 Repeated switching photocurrent-time characteristic curve of the PEC photodetector prepared by comparing the hybrid structure fabricated in Example 1 with the single two-dimensional Bi2O2S nanosheet fabricated in Example 2.

[0057] Figure 6 Photocurrent density-time characteristic curve of the hybrid structure nanosheet prepared in Example 1 of the present invention tested at different positive bias voltages. Its photocurrent density at 0 V shows the behavior of PPC. The results show that the opening condition of this PPC behavior is a short transition from a positive voltage to 0 V (negative voltage to 0 V). We speculate that a reverse driving force (DF) may always be generated at the interface between the hybrid structure and the electrolyte, forcing electrons to move in the opposite direction at 0 V.

[0058] Figure 7 Photocurrent density-time schematic diagram of the present invention tested at different light irradiances at 0 V. (40, 45, 50, 55, 60 mW / cm 2 ) The photocurrent density gradually increases from -2.8 μA / cm 2 to -3.85 μA / cm 2 , with an overall increase of 50%. This is a basic phenomenon of the continuous generation of photo-generated carriers within the range of light intensity.

[0059] Figure 8 Photocurrent density schematic diagram of the present invention tested at 0 V using KOH electrolyte solutions with different concentrations. (0.2, 0.3, 0.4, 0.5 M) From the results in the figure, it can be seen that the photocurrent density is dominant at 0.5 M, indicating that an appropriate concentration of electrolyte is more conducive to the separation of electron-hole pairs and improves the proton capture efficiency. Calculated by the formula: R = I p / PS, (R is the responsivity, I pFor photocurrent (where P and S are power density and illumination area respectively), it was found that the corresponding responsivity also showed the same effect.

[0060] Figure 9 Figure shows the impedance spectroscopy (EIS) test results at 0 V using KOH electrolyte solutions with different concentrations (0.2, 0.3, 0.4, 0.5 M). It can be seen that the impedance between the hybrid structure and the electrolyte interface is relatively small at 0.5 M, which also confirms Figure 8 the conclusion of the responsivity.

[0061] Figure 10 Figure shows the photocurrent density-time characteristic curve for testing the response time and relaxation time of the present invention at 0 V. Response time is an important parameter for evaluating the performance of a detector and should be highly regarded in electronic devices. Usually, the response time (10% - 90% of the rising edge of the photocurrent density) and the relaxation time (90% - 10% of the falling edge of the photocurrent density) are considered together. As shown in the figure, the optical response time is 0.1 s and the decay time is 0.07 s. However, due to the response time of collecting the current signal, the actual optical response time will be smaller.

[0062] Figure 11 Figure shows the photocurrent density-time characteristic curve for testing the response time and relaxation time of the present invention at 0 V using KOH electrolyte solutions with different concentrations (0.2, 0.3, 0.4, 0.5 M). As shown in the figure, there are only slight changes in its response time and relaxation time.

[0063] Figure 12 Figure shows the responsivity-photocurrent density characteristic curve for testing the photocurrent density and responsivity of the present invention at 0 V using filter films with different wavelengths (350, 365, 546, 630, 660, 700 nm, 760 nm). It can be clearly found that the photocurrent density of the device has an obvious negative optical response in the UV-Vis region. It is worth noting that at 350 nm, the optical responsivity reaches -30 mA / W.

[0064] Figure 13 Figure shows the photocurrent density-time characteristic diagram for testing the photocurrent density of the present invention by applying different bias voltages at a wavelength of 350 nm. So far, the test results have successfully proved that the PPC behavior of the present invention can be extended to a wide spectral range and cannot be adjusted by wavelength. In this regard, it is very different from the devices using wavelength modulation in the past. Compared with the detectors of PEC systems, the device based on the hybrid structure of the present invention shows excellent performance.

[0065] Figure 14Schematic diagram of photocurrent density-time characteristics obtained by testing the durability and stability of the present invention. The durability and stability of the device were determined for 4000 s.

[0066] Example 2

[0067] A method for constructing a self-powered photoelectrochemical (PEC) photodetector with a bias-driven photocurrent polarity conversion (PPC) behavior as described in Example 1, the difference being that:

[0068] In step 5), directly take 1 mg of the bismuth oxy-sulfide nanosheet sample obtained in step 3) and add it to 1 mL of NMP solution to prepare a 1 mg / mL solution, and use ultrasonic treatment until the solution is uniformly mixed. After obtaining a uniformly transparent electrolyte, it is directly used in step 6).

[0069] Figure 5 Time-photocurrent density curve of the PEC photodetector prepared from the hybrid structure involved in the present invention compared with a single two-dimensional Bi2O2S nanosheet. As can be seen from the figure, compared with a single two-dimensional Bi2O2S nanosheet, the self-powered performance of the hybrid structure is more excellent. The photocurrent density is increased by about 3 times, which is very effective in improving the device performance. Another benefit brought by this structure is as Figure 5 shown in the inset, the dark current of the device is reduced by more than 20 times (from 376 nA / cm 2 decreased to 16 nA / cm 2 ). From the perspective of the formed hybrid structure, the reason for the decrease in dark current is that relatively useless electron-hole pairs are eliminated after the contact of the two materials, thereby reducing the possibility of holes in PANI and electrons in Bi2O2S capturing protons in the electrolyte. This is an amazing change for PEC-type photosensitive devices, greatly improving the performance of the photodetector.

Claims

1. A method for constructing a self-powered photoelectrochemical (PEC) photodetector with a bias-driven photocurrent polarity conversion (PPC) behavior, comprising the following steps: 1) Pour 100 mg of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) and 20 ml of deionized water into a 50-ml volumetric beaker A. Place beaker A under ultrasonic treatment to make the internal mixture more uniform until completely dissolved. Let beaker A stand for a period of time to ensure that no precipitation occurs; 2) Mix 1 ml of hydrazine hydrate (N2H4·H2O) and 12.7 mg of thiourea in beaker B and ultrasonically treat for 2 hours to fully mix the materials; 3) Take the solution in beaker A obtained in step 1) and mix it with the solution in beaker B obtained in step 2). Add 120 mg of potassium hydroxide and 320 mg of sodium hydroxide and continuously stir for 30 minutes. Let it stand overnight, then collect the dark precipitate and wash it 3 times with deionized water and alcohol respectively. Finally, dry it in a vacuum drying oven at 70 °C for 12 h to collect pure bismuth oxysulfide Bi2O2S nanosheet powder; 4) Weigh a certain amount of PANI and the Bi2O2S nanosheet powder obtained in step 3), and continue to ultrasonically treat for several hours at room temperature. Centrifuge to collect the obtained pure hybrid structure product, and then dry it for 12 h; 5) Take 1 mg of the hybrid structure sample obtained in step 4) and add it to 1 ml of NMP solution to prepare a 1-mg / ml solution, and use ultrasonic treatment until the solution is evenly mixed; 6) Spin-coat the solution sample obtained in step 5) on the conductive ITO surface at a constant speed. The spin-coating area is 1 cm * 1 cm, then place it in an oven and let it stand for 24 h. After drying, place the device under ambient conditions and let it stand for several hours; 7) Perform photoelectric performance tests on the photodetector obtained in step 6). The test system uses an electrochemical workstation with a three-electrode system of a working electrode, a counter electrode, and a reference electrode; 8) Repeat the experiment by changing the parameters of the flexible optoelectronic detector voltage test in step 7). The changed parameters are that the electrolyte solution during the test is a KOH solution with a concentration of 0.2 mol / L - 0.5 mol / L, the light source is a xenon lamp, and the light intensity is 40 - 60 mW / cm 2 , and use filters with different wavelengths to test external light of different wavelengths; 9) Perform cyclic tests on the sample for 4000 s under the parameters set in step 8).

2. A method for constructing a self-powered photoelectrochemical (PEC) photodetector with a bias-driven photocurrent polarity conversion (PPC) behavior, characterized in that, In step 1), the ultrasonic treatment time is 2 h.

3. A method for constructing a self-powered photoelectrochemical (PEC) photodetector with a biased-driven photocurrent polarity conversion (PPC) behavior, characterized in that, In step 4), the mass of the bismuth oxysulfide sample used is 2 mg, the volume of PANI is 2 ml, the ultrasonic time is 2 h, and the number of centrifugation treatments is three times.

4. A method for constructing a self-powered photoelectrochemical (PEC) photodetector with a bias-driven photocurrent polarity conversion (PPC) behavior, characterized in that, In step 5), the ultrasonic treatment time is 2 h.

5. A method for constructing a self-powered photoelectrochemical (PEC) photodetector with a bias-driven photocurrent polarity conversion (PPC) behavior, characterized in that, In step 6), the volume of the spin-coated hybrid structure solution is 0.2 ml, the concentration is 1 mg / ml, the drying temperature in the oven is 60 °C, the drying time is 24 h, and the standing time at room temperature is 4 h.

6. A method for constructing a self-powered photoelectrochemical (PEC) photodetector with a biased-driven photocurrent polarity conversion (PPC) behavior, characterized in that, In step 8), the KOH solution used as the electrolyte solution during the test was tested at concentrations of 0.2 M, 0.3 M, 0.4 M, and 0.5 M respectively. The best phenomenon was observed at a concentration of 0.5 mol / L. The test was carried out using filter wavelengths of 350 nm, 365 nm, 546 nm, 630 nm, 660 nm, 700 nm, and 760 nm respectively. The selected light intensities during the test were 40 mW / cm 2 , 45 mW / cm 2 , 50 mW / cm 2 , 55 mW / cm 2 , 60 mW / cm 2 .

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