A flexible ZnO / CsPbBr3 QD photodetector for monitoring the light intensity received by plants

Abstract

The application provides a flexible ZnO / CsPbBr3 QD photoelectric detector for monitoring the light intensity received by plants, and belongs to the technical field of plant light intensity monitoring. The flexible ZnO / CsPbBr3 QD photoelectric detector is prepared by laser etching and processing indium tin oxide electrode material on a flexible PET substrate to form a flexible ITO / PET substrate, growing ZnO nanorods on the flexible ITO / PET substrate, and then spin coating and attaching CsPbBr3 QD dispersion liquid on the ZnO nanorods. The flexible photoelectric detector is attached to the leaves of plants as a flexible device, the change rule of the light intensity and the photocurrent is determined by the change of the photocurrent of the photoelectric detector with time, and the light intensity received by plants is continuously monitored. The flexible photoelectric detector has good flexibility, mechanical durability and stability, better portability and low manufacturing cost as a flexible device.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of plant light intensity monitoring, and particularly relates to a flexible ZnO / CsPbBr3 QD photoelectric detector for monitoring light intensity received by plants. BACKGROUND

[0002] Perovskite materials are increasingly attracting attention of photoelectric devices due to their large absorption coefficient, high carrier mobility, long exciton diffusion length and other advantages. Photoelectric detectors based on low-dimensional inorganic perovskite materials have good environmental stability in air and can realize high-sensitivity and fast-response photoelectric detectors. However, as flexible electronic devices become a research hotspot, higher requirements are put forward for low cost, softness, firmness and excellent unique optical properties of flexible photoelectric detectors, which also reveals the defects of the performance of flexible photoelectric detectors. The problems faced by flexible photoelectric detectors mainly include: 1. high cost and complicated preparation process; 2. insufficient development of materials for preparing flexible devices; 3. inability to meet the small size and stability requirements of flexible devices; and 4. limited application of flexible devices. Therefore, new breakthroughs need to be made in the field of flexible photoelectric detection technology, and various applications of flexible photoelectric detectors need to be broadened.

[0003] In 2020, Wang H, Zhang P, Zang Z. High performance CsPbBr3 quantum dots photodetectors by using zinc oxide nanorods arrays as an electron-transport layer [J]. Applied physics letters, 2020, 116 (16). It is disclosed that a ZnO seed layer with a thickness of 20 nm is deposited on washed indium tin oxide (ITO) by pulsed laser deposition, quantum dots (QD) are slowly spin-coated on ZnO nanorods (ZnO NRs), and Ag is evaporated after spin-coating an organic layer. The finally prepared ZnO NRs / CsPbBr3 quantum dot photodetector has good response parameters, and has a broad application prospect in the future. In 2019, Zheng J, Luo C, Shabbir B, et al. Flexible photodetectors based on reticulated SWNT / perovskite quantum dot heterostructures with ultrahigh durability [J]. Nanoscale, 2019, 11 (16): 8020-8026. It is disclosed that a high-performance flexible photodetector is prepared, which is composed of a reticulated SWNT (single-walled carbon nanotube) film covered with a CsPbI3 perovskite colloidal quantum dot film. The flexible device has repeated bending and stretching properties, as well as good stability, indicating its applicability as a large-area wearable flexible photodetector. At present, there is no report on the preparation of perovskite flexible photodetector for monitoring the light intensity received by plants. SUMMARY

[0004] In view of the problems of the prior art, the present application prepares a flexible ZnO / CsPbBr3 QD photodetector with good flexibility and stability, and applies it as a flexible device for testing the light intensity received by plants. The flexible device is attached to the leaves of plants, the plants are irradiated with LED plant lamps of different colors, and the light intensity received by the plants is represented by the change of the photocurrent of the flexible photodetector with time. The flexible device can be used to continuously monitor the light intensity received by plants under different environmental light intensities.

[0005] The purpose of the present application is achieved by the following technical solutions:

[0006] The application provides a flexible ZnO / CsPbBr3 QD photoelectric detector for monitoring the light intensity received by plants, which is prepared by laser etching and processing indium tin oxide (ITO) electrode material on a flexible PET substrate to form a flexible ITO / PET substrate, growing ZnO nanorods (ZnO NRs) on the flexible ITO / PET substrate, and then spin-coating and attaching a CsPbBr3 QD dispersion liquid on the ZnO nanorods.

[0007] Further, the electrode channel of the laser etching and processing indium tin oxide electrode material has a length L of 2 mm and a width W of 0.05 mm; and the thickness of the flexible ITO / PET substrate is 0.125 mm.

[0008] Further, the CsPbBr3 QD dispersion liquid is obtained by uniformly dispersing CsPbBr3 QDs in n-hexane.

[0009] Further, the ZnO nanorods are synthesized by a hydrothermal method, and the average length of the ZnO nanorods is 2 μm.

[0010] Preferably, the ZnO nanorods are synthesized by a hydrothermal method and grown on the flexible ITO / PET substrate, and the method comprises the following steps:

[0011] Zinc acetate is dissolved in methanol and ultrasonically dissolved for 5 min, stirred at 60°C for 30 min, at the same time, a NaOH solution is prepared in the methanol solution and ultrasonically treated for 30 min, the NaOH is used as a reducing agent, heated at 60°C for 5 min, and then the NaOH solution is added dropwise into the zinc acetate solution, stirred at 60°C for 2 h by a magnetic stirrer to obtain a ZnO nanorod seed solution; the ZnO nanorod seed solution is spin-coated on a clean flexible ITO / PET substrate, and the flexible ITO / PET substrate is sintered in a tube furnace at 140°C for 30 min; equal molar Zn(NO3)2·6H2O and hexamethylenetetramine (HMTA) are dissolved in deionized water and ultrasonically treated for 5 min, the sintered flexible ITO / PET substrate is placed in an oil bath cup, and the Zn(NO3)2·6H2O and hexamethylenetetramine (HMTA) solution is poured into the oil bath cup, stirred at 95°C for 6 h by a magnetic stirrer, and finally dried in an oven to obtain ZnO nanorods grown on the flexible ITO / PET substrate.

[0012] Further, the CsPbBr3 QD dispersion liquid is synthesized by a hot injection method.

[0013] Preferably, the CsPbBr3 QD dispersion liquid is synthesized by a hot injection method, including the following steps: first, CsCO3, octadecene and oleic acid are put into a three-necked flask, nitrogen is used as a protective gas, an oil bath is used at 120℃, magnetic stirring is used for 1h, the temperature is raised to 150℃, and stirring reaction is used for 3h to form a cesium oleate solution; second, PbBr2 and octadecene are put into a three-necked flask to obtain a crude solution, nitrogen is used as a protective gas, drying is used at 120℃ for 0.5h, then the crude solution is quickly injected with oleic acid and oleylamine to obtain a PbBr2 mixed solution, the cesium oleate solution is quickly injected into the PbBr2 mixed solution after preheating at 150℃ for 5s, and the three-necked flask is immediately cooled in an ice water bath to ensure that the CsPbBr3 QD crude solution obtained by the reaction is crystallized; finally, tert-butyl alcohol is added to centrifugally separate the CsPbBr3 QD crude solution twice, the rotation speed and time are 12000r and 4min, respectively, and 8000r and 4min, respectively, the supernatant is discarded, and after purification, n-hexane is added to the centrifugal tube to make the CsPbBr3 QD uniformly dispersed in the n-hexane solvent to obtain the CsPbBr3 QD dispersion liquid.

[0014] Further, a preparation method of a flexible ZnO / CsPbBr3 QD photoelectric detector, the CsPbBr3 QD dispersion liquid synthesized by the hot injection method is attached to the ZnO nanorod synthesized by the hydrothermal method by spin coating at 3000r for 20s and 3 times, and then placed on a heating table at 80℃ for 1min-2min.

[0015] Further, the flexible ZnO / CsPbBr3 QD photoelectric detector is used for monitoring the light intensity received by plants, and the monitoring method includes the following steps:

[0016] (1) An awning is built, plant seedlings are placed in the awning, a plant light supplement lamp support is built, and a plant LED lamp is placed on the plant light supplement lamp support, and the plant light supplement lamp support is used for adjusting the height between the plant light and the plants;

[0017] (2) A resistor R with the same resistance value as the flexible ZnO / CsPbBr3 QD photoelectric detector is welded to a circuit board, the circuit board, the flexible ZnO / CsPbBr3 QD photoelectric detector and a data acquisition card are connected in parallel to a power supply to form a circuit loop; the resistance value of the flexible ZnO / CsPbBr3 QD photoelectric detector and the resistor R on the circuit board is equal, so that the voltage across the resistor R and the voltage across the flexible ZnO / CsPbBr3 QD photoelectric detector are the same;

[0018] (3) connecting the data acquisition card and the computer, and the data acquisition system software is Smacq USB-5000 Series DAQ;

[0019] (4) using 80 mu m thickness double-sided transparent tape to paste the flexible ZnO / CsPbBr3 QD photodetector on the leaves of the plant seedlings;

[0020] (5) turning on the switch of the plant LED lamp, adjusting the height of the plant light supplementing lamp support to change the light intensity, obtaining the light power density value of the flexible ZnO / CsPbBr3 QD photodetector irradiated on the leaves of the plant seedlings by the light power meter, and recording the data;

[0021] (6) collecting the voltage change with time under different light intensities by the Smacq USB-5000 Series DAQ system software, calculating the current value according to the resistance value of the voltage and the resistance R by using Ohm's law, and recording the change rule of the photocurrent-time characteristic curve monitored by the flexible ZnO / CsPbBr3 QD photodetector;

[0022] (7) changing the color light of the plant LED lamp and adjusting different light power densities, according to the regular and significant change of the photocurrent, processing the data and drawing, recording the change rule of the light intensity and the photocurrent in the monitoring experiment, and further determining the most suitable light intensity received by the plant seedlings under different light in the growth process.

[0023] Further, the plant seedlings in step (1) are tomato seedlings, and the plant light supplementing lamp support is a single-row support.

[0024] Further, the color light of the LED lamp in step (7) includes white light, purple light or blue light.

[0025] Advantages and effects of the application:

[0026] Compared with the ZnO / CsPbBr3 QD photodetector in the prior art, the flexible ZnO / CsPbBr3 QD photodetector with ITO / PET as the substrate is prepared, and the preparation process is very simple, which not only can maintain excellent light detection ability and specific light detection range, compared with rigid devices, as a flexible device, has good flexibility, mechanical durability and stability, better portability and low manufacturing cost;

[0027] The flexible ZnO / CsPbBr3 QD photoelectric detector prepared by the application is used for monitoring the light intensity received by plants, and based on the photoelectric detector, the flexible device can be attached to the plant leaves, under different light intensities, the light intensity received by plants is reflected by the change of the photoelectric current of the flexible photoelectric detector, and according to the change rule of the light intensity and the photoelectric current, the light intensity received by plants under different environmental light intensities is continuously monitored; when the flexible ZnO / CsPbBr3 QD photoelectric detector is used for monitoring the light intensity of plant leaves, the flexible ZnO / CsPbBr3 QD photoelectric detector can be well attached to the plant leaves, and almost no influence is caused to the plants during the test, so that no other interference factors are caused to the experimental results.

[0028] The flexible ZnO / CsPbBr3 QD photoelectric detector is used for continuously monitoring the change of the light intensity received by plants in the growth process, so as to determine the most suitable light intensity for the plant seedlings in the growth process. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a scanning electron microscope (SEM) image of the ZnO nanorod in Example 1.

[0030] Figure 2 It is a transmission electron microscope (TEM) image of the CsPbBr3 QD attached to the ZnO nanorod in Example 1.

[0031] Figure 3 It is a scanning electron microscope (SEM) image of the CsPbBr3 QD attached to the ZnO nanorod in Example 1.

[0032] Figure 4 It is a comparative spectrum diagram of the flexible ZnO / CsPbBr3 QD photoelectric detector in Example 1 and the existing CsPbBr3 QD, wherein Fig. (a) is an absorption spectrum diagram, and Fig. (b) is a photoluminescence spectrum (PL) diagram.

[0033] Figure 5 It is a preparation process schematic diagram of a flexible ZnO / CsPbBr3 QD photoelectric detector in Example 1.

[0034] Figure 6 It is a real object diagram of a flexible ZnO / CsPbBr3 QD photoelectric detector in Example 1 under the bending radii of 30°, 60° and 90°.

[0035] Figure 7 It is a circuit design diagram and a real object connection diagram in the method for monitoring the light intensity received by plants by using a flexible ZnO / CsPbBr3 QD photoelectric detector in Example 1, wherein Fig. (a) is a circuit design diagram, Fig. (b) is a real object connection diagram, and Fig. (c) is a real object connection diagram of the flexible ZnO / CsPbBr3 QD photoelectric detector attached to the plant leaves.

[0036] Figure 8 I-T curves of the flexible ZnO / CsPbBr3 QD photodetector in Example 1 under different bending radii after changing the number of bending cycles, wherein Figure (a) is a 30° bending radius, Figure (b) is a 60° bending radius, and Figure (c) is a 90° bending radius;

[0037] Figure 9 I-T curves of the flexible ZnO / CsPbBr3 QD photodetector in Application Example 1 under different color lights after changing the light power, wherein Figure (a) is white light, Figure (b) is blue light, and Figure (c) is purple light. DETAILED DESCRIPTION

[0038] The application will be described in detail below with reference to the examples.

[0039] Example 1

[0040] A flexible ZnO / CsPbBr3 QD photodetector is used to monitor the light intensity received by plants. The flexible ZnO / CsPbBr3 QD photodetector is prepared by laser etching ITO electrode material on a flexible PET substrate to form a flexible ITO / PET substrate, growing ZnO nanorods on the flexible ITO / PET substrate, and then spin coating CsPbBr3 QD dispersion liquid onto the ZnO nanorods. The flexible ZnO / CsPbBr3 QD photodetector is attached to the leaves of plants as a flexible device. The color and height of the LED plant lamp are adjusted to change the light intensity. The change of the photocurrent of the flexible ZnO / CsPbBr3 QD photodetector with time is combined to determine the relationship between the light intensity and the change of the photocurrent, and then the light intensity received by plants under different environmental light intensities is continuously monitored.

[0041] The ZnO nanorods are synthesized by a hydrothermal method and grown on a flexible ITO / PET substrate, including the following steps:

[0042] The ITO electrode material is laser etched on a flexible PET substrate, with an electrode channel length L = 2 mm and a width W = 0.05 mm, to obtain a flexible ITO / PET substrate with a thickness of 0.125 mm.

[0043] Dissolve 43.87 mg of ZnAc in 20 mL of methanol, ultrasonic dissolution for 5 min, and stir for 30 min at 60°C on a hot plate with a magnetic stirrer; meanwhile, prepare a NaOH solution with a mass of 72 mg in 20 mL of methanol, and ultrasonic for 30 min; use NaOH as a reducing agent, and heat for 5 min at 60°C; then, drop the NaOH solution into the ZnAc solution, and stir for 2 h at 60°C with a magnetic stirrer to prepare a ZnO nanorod seed solution; take 20 μL of the ZnO nanorod seed solution, spin at 3000 r for 20 s, and spin twice on a clean flexible ITO / PET substrate to grow ZnO nanorods on the flexible ITO / PET substrate; then, sinter the flexible ITO / PET substrate in a tube furnace at 140°C for 30 min; dissolve 535.482 mg of Zn(NO3)2·6H2O and 252.342 mg of HMTA in 60 mL of deionized water, and ultrasonic for about 5 min; place the ITO / PET flexible substrate after sintering and growth of ZnO nanorods in a tube furnace in an oil bath cup, and then pour the dissolved Zn(NO3)2·6H2O and HMTA solution, and stir magnetically at 95°C for 6 h; finally, place in an oven for drying to obtain ZnO nanorod arrays grown on a flexible ITO / PET substrate;

[0044] As shown in Figure 1 FIG. 6 is a SEM image of the ZnO nanorods synthesized by the hydrothermal method in the present embodiment, and it can be seen that the average length of the ZnO nanorods is about 2 μm.

[0045] The CsPbBr3 QD dispersion liquid is synthesized by a hot injection method, including the following steps:

[0046] First, place 0.814 g of CsCO3, 35 mL of octadecene, and 0.5 mL of oleic acid in a 250 mL three-necked flask, use nitrogen as a protective gas, 120°C oil bath, and magnetic stirring for 1 h; then, increase the temperature to 150°C, and stir for 3 h to obtain a cesium oleate solution; at the same time, mix 0.138 g of PbBr2 and 10 mL of octadecene in a 250 mL three-necked flask to obtain a crude solution, use nitrogen as a protective gas, and dry at 120°C for 0.5 h; then, quickly inject 1 mL of oleic acid and 1 mL of oleylamine into the crude solution to obtain a PbBr2 mixed solution; then, preheat the prepared cesium oleate solution at 150°C, quickly inject 0.8 mL of the cesium oleate solution into the PbBr2 mixed solution, and immediately cool the three-necked flask in an ice water bath after 5 s of reaction to ensure crystallization of the obtained CsPbBr3 QD crude solution; finally, centrifuge the CsPbBr3 QD crude solution twice by adding tert-butyl alcohol, the speed and time are 12000 r and 4 min, and 8000 r and 4 min respectively, discard the supernatant, and add 6 mL of n-hexane in the centrifuge tube after purification to make the CsPbBr3 QD uniformly dispersed in the n-hexane solvent to obtain a CsPbBr3 QD dispersion liquid.

[0047] A preparation method of a flexible ZnO / CsPbBr3 QD photoelectric detector, as shown in Figure 5 The preparation process of the flexible ZnO / CsPbBr3 QD photoelectric detector in the embodiment is as follows: ITO electrode material is laser etched and processed on a flexible PET substrate to obtain a flexible ITO / PET substrate, and ZnO nanorods are grown on the flexible ITO / PET substrate; the ZnO nanorods grown on the flexible ITO / PET substrate are placed on an 80℃ heating table for 1-2 min after being coated with a CsPbBr3 QD dispersion liquid prepared by 3 times of 3000r, 20s spin coating, to obtain the flexible ZnO / CsPbBr3 QD photoelectric detector;

[0048] As shown in Figure 2 , Figure 3 , they are TEM and SEM images of the ZnO nanorods to which CsPbBr3 QDs are attached in the embodiment, and it can be seen that the ZnO nanorods grown on the flexible ITO / PET substrate are attached with CsPbBr3 QDs, and the flexible ZnO / CsPbBr3 QD photoelectric detector is successfully prepared;

[0049] As shown in Figure 4 (a) and Figure 4 (b), they are absorption spectrum and PL emission spectrum of the ZnO / CsPbBr3 QD photoelectric detector compared with the prior art CsPbBr3 QD in the embodiment, and it can be seen that the test sample of the ZnO / CsPbBr3 QD photoelectric detector of the present application is basically consistent with the CsPbBr3 QD spectrum, in which the absorption spectrum wavelength is about 510 nm, and the emission spectrum wavelength is about 525 nm, which fully shows that the CsPbBr3 QD is successfully prepared.

[0050] A monitoring method of a flexible ZnO / CsPbBr3 QD photoelectric detector for monitoring the light intensity received by plants, comprising the following steps:

[0051] (1) A light-shielding shed with a size of 60cm×50cm×45cm is built, and one or two plant seedlings are placed in the light-shielding shed, a single-row support for a plant light supplement lamp is built, and a plant LED lamp is placed, and the single-row support can adjust the height between the plant light and the plants;

[0052] (2) Test the resistance value of the flexible ZnO / CsPbBr3 QD photodetector in this embodiment. Select a resistor R with the same resistance value as the flexible ZnO / CsPbBr3 QD photodetector and solder the resistor R to the circuit board. The circuit board, the flexible ZnO / CsPbBr3 QD photodetector and the data acquisition card are connected in parallel to the power supply to form a circuit loop. The resistance value of the flexible ZnO / CsPbBr3 QD photodetector and the resistor R on the circuit board are equal to ensure that the voltage across the resistor R and the voltage across the flexible ZnO / CsPbBr3 QD photodetector are the same.

[0053] (3) Connect the data acquisition card to the computer. The data acquisition system software is Smacq USB-5000SeriesDAQ.

[0054] (4) Use 80μm thick double-sided transparent tape to attach the flexible ZnO / CsPbBr3 QD photodetector to the leaves of the plant seedling;

[0055] (5) Turn on the switch of the plant LED light, adjust the height of the plant LED light using the single row bracket of the plant supplement light, thereby changing the light intensity, obtain the light power density value of the flexible ZnO / CsPbBr3QD photodetector irradiating the leaves of the plant seedling described in step (4) through the light power meter, and record the data;

[0056] (6) The voltage change with time under different light intensities was collected by the Smacq USB-5000Series DAQ system software. Based on the voltage and the resistance value of R, the current value was calculated using Ohm's law, and then the change law of the photocurrent-time characteristic curve monitored by the flexible ZnO / CsPbBr3 QD photodetector was recorded.

[0057] (7) Change the color of the LED light on the plant (white light, purple light or blue light) and adjust different light power densities to find regular and significant changes in photocurrent. Then, perform data processing and plotting to record the experimental law of changes in light intensity and photocurrent.

[0058] Under different light intensity conditions, the light intensity received by plants can be monitored by the change in photocurrent of flexible photodetectors during the growth process, so as to ensure that the plants receive the most suitable light intensity under different light conditions during the growth process.

[0059] according to Figure 7 (a) connects the components involved in step (2) in the circuit design diagram to obtain... Figure 7 (b) shows the physical connection diagram. Figure 7 (c) is a physical connection diagram of a flexible ZnO / CsPbBr3 QD photodetector attached to a plant seedling leaf.

[0060] Performance analysis

[0061] As Figure 6 shown, the flexible ZnO / CsPbBr3 QD photodetector 30°, 60°, 90° of the bending radius in the embodiment, it is shown that the flexible ZnO / CsPbBr3 QD photodetector prepared by the application has good flexibility;

[0062] A flexible ZnO / CsPbBr3 QD photodetector is irradiated by 405nm wavelength laser under 1V bias, and after 0, 100, 200, 300 and 400 bending cycles under 30°, 60° and 90° bending radius respectively, the I-T curve of the change of the photocurrent of the flexible ZnO / CsPbBr3 QD photodetector with time is studied, as Figure 8 shown, it can be seen that the photocurrent does not change obviously after multiple bending cycles, which further indicates that the flexible ZnO / CsPbBr3 QD photodetector of the application has good flexibility, mechanical durability and stability.

[0063] Application Example 1

[0064] According to the monitoring method of the flexible ZnO / CsPbBr3 QD photodetector for monitoring the light intensity received by plants in Example 1, the tomato seedlings are irradiated by changing the light power density under white light, blue light and violet light LED plant lamps, and the change of the photocurrent of the flexible ZnO / CsPbBr3 QD photodetector with time is studied, as Figure 9 shown, the photocurrent shows regular and significant changes, and the experimental law of the change of the light intensity and the photocurrent is recorded;According to the optimal light intensity value of the tomato seedlings (or other seedling plants) in the literature, the light intensity of the LED lamp is adjusted, and whether the plant seedlings are in the optimal light intensity is continuously monitored by observing the change of the photocurrent of the flexible ZnO / CsPbBr3 QD photodetector.

[0065] Application Example 2

[0066] According to the monitoring method of the flexible ZnO / CsPbBr3 QD photodetector for monitoring the light intensity received by plants in Example 1, different wavelength LED plant lamps are used for irradiation, the light power density is changed, and the plants are irradiated in groups, and the growth of the plants in each group is observed, so as to determine the optimal color light and light intensity of the plant seedlings in the growth process.

Claims

1. The application of a flexible ZnO / CsPbBr3 QD photodetector in monitoring the light intensity received by plants, characterized in that, The flexible ZnO / CsPbBr3 QD photodetector is fabricated by laser etching of indium tin oxide (ITO) electrode material on a flexible PET substrate. The electrode channel has a length L=2mm and a width W=0.05mm, forming a flexible ITO / PET substrate with a thickness of 0.125mm. ZnO nanopillars are grown on the flexible ITO / PET substrate, and then CsPbBr3 QD dispersion is spin-coated onto the ZnO nanopillars to complete the fabrication. The flexible ZnO / CsPbBr3 QD photodetector is attached to a plant leaf as a flexible device. The light intensity is changed by adjusting the color and height of the LED plant light. The relationship between light intensity and photocurrent is determined by combining the change of photocurrent of the flexible ZnO / CsPbBr3 QD photodetector over time, thereby continuously monitoring the light intensity received by the plant under different ambient light intensities. The CsPbBr3 QD dispersion was synthesized using a hot injection method, including the following steps: First, CsCO3, octadecene, and oleic acid were placed in a three-necked flask. Using nitrogen as a protective gas, the mixture was stirred magnetically in an oil bath at 120°C for 1 hour. The temperature was then raised to 150°C, and the reaction was continued for 3 hours with stirring to form a cesium oleate solution. Next, PbBr2 and octadecene were mixed in the three-necked flask to obtain a crude solution. Using nitrogen as a protective gas, the mixture was dried at 120°C for 0.5 hours. Then, oleic acid and oleylamine were rapidly injected into the crude solution to obtain a PbBr2 mixture. A preheated cesium oleate solution at 150°C was then rapidly injected into the PbBr2 mixture. After reacting for 5 seconds, the three-necked flask was immediately cooled in an ice-water bath to ensure the crystallization of the resulting CsPbBr3 QD crude solution. Finally, tert-butanol was added, and the CsPbBr3 QD crude solution was centrifuged twice at 12000 rpm for 4 minutes and 8000 rpm for 4 minutes, respectively. The supernatant was discarded, and after purification, hexane was added to the centrifuge tube to allow the CsPbBr3 to crystallize. QD was uniformly dispersed in n-hexane solvent to obtain CsPbBr3QD dispersion; The CsPbBr3QD dispersion synthesized by the hot injection method was spin-coated onto ZnO nanopillars synthesized by the hydrothermal method at 3000 r, 20 s, and 3 times, and then placed on an 80℃ heating stage for 1 min-2 min.

2. The application of the flexible ZnO / CsPbBr3 QD photodetector as described in claim 1 in monitoring the light intensity received by plants, characterized in that, The average length of the ZnO nanopillars synthesized by the hydrothermal method is 2 μm.

3. The application of the flexible ZnO / CsPbBr3 QD photodetector as described in claim 2 in monitoring the light intensity received by plants, characterized in that... The synthesis of ZnO nanopillars using a hydrothermal method includes the following steps: Zinc acetate was dissolved in methanol and sonicated for 5 min, then stirred at 60°C for 30 min. Simultaneously, a NaOH solution was prepared in the methanol solution and sonicated for 30 min. Using NaOH as a reducing agent, the solution was heated at 60°C for 5 min, and then the NaOH solution was added dropwise to the zinc acetate solution. The mixture was stirred with a magnetic stirrer at 60°C for 2 h to obtain a ZnO nanopillar seed solution. The ZnO nanopillar seed solution was spin-coated onto a clean flexible ITO / PET substrate, and the flexible ITO / PET substrate was sintered in a tube furnace at 140°C for 30 min. Equimolar amounts of Zn(NO3)2·6H2O and hexamethylenetetramine were dissolved in deionized water and sonicated for 5 min. The sintered flexible ITO / PET substrate was placed in an oil bath, and the dissolved Zn(NO3)2·6H2O and hexamethylenetetramine solution was poured in. The mixture was stirred with a magnetic stirrer at 95°C for 6 h, and finally dried in an oven to obtain ZnO nanopillars grown on a flexible ITO / PET substrate.

4. The application of the flexible ZnO / CsPbBr3 QD photodetector as described in claim 1 in monitoring the light intensity received by plants, characterized in that... The monitoring method includes the following steps: (1) Set up a shade shed, place the plant seedlings inside the shade shed, set up a plant grow light bracket, and place a plant LED light on the plant grow light bracket. The plant grow light bracket is used to adjust the height between the plant light and the plant. (2) Select a resistor R with the same resistance value as the flexible ZnO / CsPbBr3QD photodetector, and solder the resistor R to the circuit board. The circuit board, the flexible ZnO / CsPbBr3QD photodetector and the data acquisition card are connected in parallel to the power supply to form a circuit loop. (3) Connect the data acquisition card to the computer. The data acquisition system software is Smacq USB-5000 SeriesDAQ. (4) Use double-sided transparent tape with a thickness of 80μm to attach the flexible ZnO / CsPbBr3 QD photodetector to the leaves of the plant seedling; (5) Turn on the switch of the plant LED light, adjust the height of the plant LED light using the plant supplement light bracket to change the light intensity, obtain the light power density value of the flexible ZnO / CsPbBr3QD photodetector illuminating the leaves of the plant seedling through the light power meter, and record the data; (6) The voltage change with time under different light intensities was collected by the Smacq USB-5000 Series DAQ system software. Based on the voltage and the resistance value of R, the current value was calculated using Ohm's law, and then the change law of the photocurrent-time characteristic curve monitored by the flexible ZnO / CsPbBr3QD photodetector was recorded. (7) Change the color of the LED light of the plant and adjust different light power densities. Based on the regular and significant changes in photocurrent, perform data processing and plotting, record the changes in light intensity and photocurrent in the monitoring experiment, and then determine the most suitable light intensity for the plant seedlings under different light conditions during the growth process.

5. The application of the flexible ZnO / CsPbBr3 QD photodetector as described in claim 4 in monitoring the light intensity received by plants, characterized in that... The plant seedlings mentioned in step (1) are tomato seedlings, and the plant grow light brackets are single-row brackets.

6. The application of the flexible ZnO / CsPbBr3 QD photodetector as described in claim 4 in monitoring the light intensity received by plants, characterized in that... The LED light in step (7) includes white light, purple light or blue light.

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