Application of device structure based on chlorophyll derivative in photoelectric detector

Abstract

The invention relates to application of a device structure based on a chlorophyll derivative to a photoelectric detector, and belongs to the technical field of device application. A new application mode of the device structure based on the chlorophyll derivative in the field of photoelectric detection is found for the first time, and the photoelectric detector based on the device structure of the chlorophyll derivative can realize an image sensing function. The photoelectric detector based on the device structure of the chlorophyll derivative has a rapid bidirectional current response behavior. By using a background subtraction method, a motion detection function is realized by constructing a quasi-plane heterojunction organic photoelectric detector array. The photoelectric detector based on the device structure of the chlorophyll derivative provides a good foundation for developing multifunctional organic photoelectric detector equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of device application, and in particular relates to the application of a device structure based on chlorophyll derivatives in a photoelectric detector. Background Art

[0002] With the advent of the Internet of Things era, people's demand for a safe, intelligent and convenient environment is becoming increasingly strong. As an emerging technology for future intelligence, dynamic detection plays a vital role in security monitoring and traffic management, such as real-time obstacle detection and avoidance. In addition, electronic components based on this technology are required to have high sensitivity and resolution characteristics. Photodetectors have the advantages of fast response speed, wide response range, low noise, and integrability, and are considered to be potential devices for realizing dynamic detection functions. Among them, organic photodetectors have the advantages of adjustable spectral response, environmental friendliness, and good biocompatibility, and are considered to be an important direction for the development of photodetectors in the future. Therefore, people are committed to the research and development of new structures of organic photodetectors, or the development of new applications for existing device structures.

[0003] Chlorophyll is a natural organic semiconductor material with the characteristics of high photoelectric conversion efficiency and wide spectral absorption range. As far as we know, single-molecule chlorophyll derivatives can self-assemble into aggregates to expand the absorption range to the near infrared. Therefore, chlorophyll and its derivatives have attracted a lot of research, such as solar cells and photocatalysis. For example, Chinese patent document CN109346602B discloses an efficient double-layer structure organic solar cell based on chlorophyll aggregates, which includes a transparent conductive glass cathode, an electron transport layer, a chlorophyll aggregate layer, a fullerene derivative layer, a hole transport layer and a metal anode from bottom to top, achieving a photoelectric conversion efficiency of up to 5.3%. The efficient double-layer structure based on chlorophyll aggregates is used as a solar cell, and its purpose is to convert chemical energy into electrical energy and then generate electricity.

[0004] However, to date, there is no report in the prior art on the application of the above-mentioned efficient double-layer structure based on chlorophyll aggregates in photodetectors. Summary of the invention

[0005] In view of this, the present invention has discovered a new application mode of the device structure based on chlorophyll derivatives in the field of photoelectric detection, and further provides an application of the device structure based on chlorophyll derivatives in photoelectric detectors. The photoelectric detector based on the device structure of chlorophyll derivatives exhibits bidirectional current behavior in the near-infrared region under different bias voltages. Based on the above experimental phenomena, the image sensing and motion detection functions are realized by constructing a quasi-planar heterojunction organic photodetector array; the motion detection function uses background subtraction method to realize the extraction of moving targets from the image stream.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] A device structure based on chlorophyll derivatives is used in a photodetector, wherein the device structure based on the chlorophyll derivatives comprises, from bottom to top, a transparent conductive glass cathode, an electron transport layer, a quasi-planar heterojunction layer, a hole transport layer and a metal anode; the quasi-planar heterojunction layer comprises, from bottom to top, a chlorophyll derivative (Chl) and a fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PC 61 BM).

[0008] Furthermore, photodetectors based on the device structure of chlorophyll derivatives can realize image sensing and motion detection functions.

[0009] Furthermore, the motion detection function uses background subtraction to extract moving objects from the image stream.

[0010] Furthermore, the electron transport layer is zinc oxide, the hole transport layer is molybdenum oxide, the transparent conductive glass cathode is tin-doped indium tin oxide ITO, and the metal anode is Ag.

[0011] Furthermore, the thickness of the electron transport layer is 50 nanometers; the thickness of the quasi-planar heterojunction layer is 79 nanometers, of which the thickness of the chlorophyll derivative (Chl) layer is 33 nanometers, and the thickness of the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PC 61 The thickness of the BM) layer is 46 nanometers; the thickness of the hole transport layer is 10 nanometers; and the thickness of the metal anode is 100 nanometers.

[0012] The beneficial effects of the present invention are:

[0013] The present invention discovers for the first time a new application mode of the device structure based on chlorophyll derivatives in the field of photoelectric detection. The photoelectric detector based on the device structure of chlorophyll derivatives can realize the image sensing function.

[0014] The photodetector based on the device structure of chlorophyll derivatives has fast bidirectional current response behavior. Using background subtraction method, motion detection function is realized by constructing a quasi-planar heterojunction organic photodetector array.

[0015] Photodetectors based on the device structure of chlorophyll derivatives provide a good foundation for the development of multifunctional organic photodetector devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0017] Figure 1It is a structural diagram of the photoelectric detection device based on chlorophyll derivatives prepared by the present invention.

[0018] Figure 2 It is an energy band structure diagram of the photoelectric detection device based on chlorophyll derivatives prepared by the present invention.

[0019] Figure 3 1 is an image sensing function diagram of the photoelectric detection device based on chlorophyll derivatives prepared by the present invention, wherein Figure (a) is a schematic diagram of the measurement configuration, and Figures (b) and (c) are the corresponding two-dimensional current density diagrams under dark state and white light irradiation, respectively.

[0020] Figure 4 It is the bidirectional photocurrent behavior of the photoelectric detection device based on chlorophyll derivatives prepared by the present invention.

[0021] Figure 5 This is a diagram of the simulated motion detection function of the photoelectric detection device array based on chlorophyll derivatives prepared by the present invention, wherein Figure (a) shows the process of detecting a moving object, Figure (b) shows the position and posture of a runner at different times, and Figure (c) shows the pixel distribution at different times. DETAILED DESCRIPTION

[0022] The following will introduce in more detail the device structure based on chlorophyll derivatives of the present invention, which can realize image sensing and motion detection functions in photodetectors, in conjunction with the accompanying drawings and embodiments.

[0023] The present invention provides an application of a device structure based on a chlorophyll derivative in a photodetector, wherein the device structure based on the chlorophyll derivative comprises, from bottom to top, a transparent conductive glass cathode, an electron transport layer, a quasi-planar heterojunction layer, a hole transport layer and a metal anode; the quasi-planar heterojunction layer comprises, from bottom to top, a chlorophyll derivative (Chl) and a fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PC 61 BM). The electron transport layer is zinc oxide, the hole transport layer is molybdenum oxide, the transparent conductive glass cathode is tin-doped indium tin oxide ITO, and the metal anode is Ag. The thickness of the electron transport layer is 50 nanometers; the thickness of the quasi-planar heterojunction layer is 79 nanometers (of which the thickness of the Chl layer is about 33 nanometers, and the thickness of the PCl layer is about 10 nanometers). 61 The thickness of the BM layer is 46 nanometers); the thickness of the hole transport layer is 10 nanometers; and the thickness of the metal anode is about 100 nanometers.

[0024] The chlorophyll derivative (Chl) and the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PC 61 The molecular formula structures of BM are as follows:

[0025]

[0026] The photoelectric detector of the device structure based on chlorophyll derivatives of the present invention is prepared as follows:

[0027] 1) Treatment of transparent conductive glass cathode:

[0028] The cleaned transparent conductive glass ITO was treated with ozone for 20 minutes;

[0029] 2) Preparation of electron transport layer:

[0030] The transparent conductive glass treated in step 1) is placed on a coating machine and spin-coated with a zinc oxide layer. The spin-coating process is 4000 rpm for 30 seconds to form a zinc oxide precursor film. The glass is then immediately placed on a hot plate for annealing. The annealing temperature and time are 200° C. for 60 minutes.

[0031] 3) Preparation of quasi-planar heterojunction layer:

[0032] The conductive substrate cooled to room temperature after annealing was transferred to a glove box filled with nitrogen, and a Chl layer was drop-coated on a coater. The drop-coating process was 3000 rpm for 40 seconds to form a Chl film, and then it was immediately placed on a hot stage for annealing. The annealing temperature and time were 45°C for 3 minutes. The sample cooled to room temperature was then transferred to a coater for further spin coating of PC 61 The BM layer was spin-coated at 1500 rpm for 30 seconds to form the PC 61 The BM film is then immediately placed on a hot stage for annealing at 45°C for 3 minutes.

[0033] 4) Preparation of hole transport layer:

[0034] Using organic evaporation coating machine at a pressure less than 6*10 -4 When on PC 61 The hole transport layer molybdenum oxide is evaporated on the BM layer, and its evaporation rate is

[0035] 5) Preparation of metal anode:

[0036] Using organic evaporation coating machine at a pressure less than 6*10 -4 When the metal anode Ag is evaporated on the hole transport layer, the evaporation rate is

[0037] In the above preparation process, the preparation process of the zinc oxide precursor solution is as follows:

[0038] 0.2 g of zinc acetate dihydrate was dissolved in 2 mL of ethylene glycol methyl ether containing 56 μL of ethanolamine, and stirred at room temperature in the dark for 12 hours for use.

[0039] The preparation process of chlorophyll derivative (Chl) solution is as follows:

[0040] The Chl particles were dissolved in tetrahydrofuran and stirred at room temperature in the dark until dissolved to obtain a solution of Chl with a concentration of 9 mg / mL;

[0041] The fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PC 61 The preparation process of BM solution is as follows:

[0042] PC 61 The BM particles were dissolved in a chloroform:chlorobenzene = 2:1 (volume ratio) solution and stirred at room temperature in the dark until dissolved to obtain a PC solution with a concentration of 15 mg / mL. 61 BM solution.

[0043] The organic photodetector array of the device structure based on chlorophyll derivatives of the present invention can realize image sensing and motion detection functions, and the process is as follows:

[0044] 1) Bidirectional photocurrent characteristics of the device:

[0045] Under 780-nanometer light, bias voltages of -0.3V and 1V were applied to the device, respectively, and the current changes under light were recorded and compared. The photocurrent response of the device was negative under -0.3V light, and the photoelectric response of the device was positive under 1V light, indicating that the device exhibited bidirectional photocurrent behavior.

[0046] 2) Linear relationship of the device:

[0047] Under different intensities of 780-nanometer light, the device was applied with bias voltages of -0.3V and 1V, respectively, and the change in photocurrent density was linearly correlated with the light intensity.

[0048] 3) Motion detection function of the device:

[0049] Taking a runner as the detection object, the image pixels at different times are extracted by simulation method. The linear relationship obtained under the bias voltage of 1V and -0.3V is applied to the pixel matrix to obtain the positive and negative photocurrent density matrix. The background subtraction method is used to adjust the pixels to the range of 0-255 to obtain the final motion detection image.

[0050] The basic principle of the bidirectional photocurrent behavior of the photodetector based on chlorophyll derivatives provided by the present invention is as follows:

[0051] When the quasi-planar heterojunction organic photodetector is illuminated by 780 nm light, PC 61The near-UV-visible-near-infrared absorption spectrum of BM shows negligible absorption. Therefore, to simplify the physical mechanism of the bidirectional current behavior, we consider that the photogenerated excitons exist in the Chl layer as the main light absorption layer. Under reverse bias voltage conditions, the device operates in the hole accumulation mode under 780 nm light illumination. The Chl layer absorbs light and generates electron-hole pairs. According to the Chl and PC 61 The energy level and electric field distribution of BM show that in Chl and PC 61 At the interface of BM, photogenerated holes accumulate and photogenerated electrons transfer from Chl to the metal anode, generating a negative photocurrent. In contrast, when irradiated at a forward bias voltage of 780 nm, the device operates in the electron accumulation mode. Photogenerated holes recombine with externally injected electrons, and photogenerated electrons transfer from Chl to the metal anode, generating a negative photocurrent. 61 Due to the energy level and electric field distribution, the light aggregates at the interface of BM, forming a forward photocurrent.

[0052] Example 1

[0053] The ITO glass was cleaned with detergent for 30 minutes, and then rinsed thoroughly with deionized water until there was no foam. Subsequently, it was rinsed in acetone, isopropanol, and ethanol for 30 minutes in sequence. Then, a zinc oxide precursor solution was prepared by dissolving 0.2 g of zinc acetate in 2 mL of 2-methoxyethanol, adding 56 μL of ethanolamine as a stabilizer, and stirring for 12 hours to obtain a zinc oxide precursor solution. In a glove box, Chl was dissolved in tetrahydrofuran solvent (9 mg / mL), stirred at room temperature until dissolved, and a Chl solution with a concentration of 9 mg / mL was prepared. PC 61 BM was dissolved in chloroform and chlorobenzene (volume ratio of 2:1) and stirred at room temperature on a stirrer to prepare a PC solution with a concentration of 15 mg / mL. 61 BM solution. After treating ITO with ozone for 20 minutes, place it on a coater and spin-coat the zinc oxide precursor solution at 4000rpm for 30 seconds to form a precursor film with a thickness of 50 nanometers. Then immediately place it on a heating table for annealing. The annealing temperature and time are 200℃ for 60 minutes. The conductive substrate that has been cooled to room temperature after annealing is sent to a glove box. First, Chl is dripped on the ZnO layer at 3000rpm and rotated for 40 seconds to form a Chl layer with a thickness of about 33 nanometers. Then anneal at 45℃ for 3 minutes. The substrate that has been cooled to room temperature is then transferred to the coater for spin coating of PC 61 The BM solution was drop-coated on the Chl layer and rotated at 1500 rpm for 30 seconds to form the PC 61 BM layer, PC 61 The thickness of the BM layer is 46 nanometers, and then annealed at 45°C for 3 minutes. Then the substrate is sent to an organic evaporation coating machine to evaporate the hole transport layer of molybdenum oxide, and its evaporation rate is The co-evaporation film thickness is 10 nanometers; then the metal electrode Ag is evaporated, and its evaporation rate is The co-evaporation film thickness is 100nm. Thus, a biophotodetector using chlorophyll derivatives and having a quasi-planar heterojunction interface is obtained. The device structure diagram and energy band structure diagram are respectively shown in Figure 1 and 2 .

[0054] Example 2

[0055] 1) Bidirectional photocurrent characteristics of the device prepared in Example 1:

[0056] Under 780 nm light, bias voltages of -0.3 V and 1 V were applied to the device, and the current changes under light were recorded and compared. The photocurrent response of the device under -0.3 V light was negative, and the photoelectric response of the device under 1 V light was positive. The device exhibited bidirectional photocurrent behavior, see Figure 4 .

[0057] 2) Linear relationship of the device prepared in Example 1:

[0058] Under different intensities of 780-nanometer light, the device was applied with bias voltages of -0.3V and 1V, respectively, and the change in photocurrent density was linearly correlated with the light intensity.

[0059] 3) Motion detection function of the device prepared in Example 1:

[0060] Taking a runner as the detection object, the image pixels at different times are extracted by simulation method. The linear relationship obtained under the bias voltage of 1V and -0.3V is applied to the pixel matrix to obtain the positive and negative photocurrent density matrix. The background subtraction method is used to adjust the pixels to the range of 0-255 to obtain the final motion detection image.

[0061] Figure 3 a shows the design of a 20×20 photodetector array for an optical image sensor to evaluate the feasibility of integrating quasi-planar heterojunction organic photodetectors into the system. The bright and dark current densities of all pixels are measured separately in the self-driven mode, see Figure 3 b and c.

[0062] Based on the bidirectional current behavior of quasi-planar heterojunction organic photodetectors, an organic photodetector array for motion detection was constructed, see Figure 5 a. Detect moving objects at different times and the corresponding pixel distribution results, see Figure 5 b and c. Pixel distribution changes over time depending on the runner’s position and posture.

[0063] In summary, the photodetector based on the device structure of chlorophyll derivatives exhibits bidirectional current behavior in the near-infrared region under different bias voltages. Based on the above experimental phenomena, the image sensing and motion detection functions are realized by constructing a quasi-planar heterojunction organic photodetector array; the motion detection function uses the background subtraction method to extract the moving target from the image stream. The present invention lays a solid foundation for promoting the development of multifunctional organic photodetectors.

[0064] The above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. Application of a device structure based on a chlorophyll derivative in a photodetector, wherein the device structure based on the chlorophyll derivative comprises from bottom to top: A transparent conductive glass cathode, an electron transport layer, a quasi-planar heterojunction layer, a hole transport layer and a metal anode; the quasi-planar heterojunction layer is composed of a chlorophyll derivative and a fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester from bottom to top.

2. The use according to claim 1, characterized in that: Photodetectors based on chlorophyll derivative device structures can realize image sensing and motion detection functions.

3. The use according to claim 1, characterized in that: The motion detection function uses background subtraction to extract moving targets from the image stream.

4. The use according to any one of claims 1 to 3, characterized in that: The electron transport layer is zinc oxide, the hole transport layer is molybdenum oxide, the transparent conductive glass cathode is tin-doped indium tin oxide ITO, and the metal anode is Ag.

5. The use according to any one of claims 1 to 3, characterized in that: The thickness of the electron transport layer is 50 nanometers; the thickness of the quasi-planar heterojunction layer is 79 nanometers, of which the thickness of the chlorophyll derivative layer is 33 nanometers, and the thickness of the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester layer is 46 nanometers; the thickness of the hole transport layer is 10 nanometers; and the thickness of the metal anode is 100 nanometers.

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