Full-flexible solar-blind ultraviolet light detection material and preparation method and application thereof

Abstract

The invention belongs to the technical field of solar-blind ultraviolet light detection materials, and relates to a full-flexible solar-blind ultraviolet light detection material and a preparation method and application thereof, and the full-flexible solar-blind ultraviolet light detection material comprises a down-conversion luminescent material, an azobenzene polymer and a piezoelectric polymer. The excitation-emission characteristic of the rare earth doped down-conversion particles is utilized, a light absorption window of azobenzene elements and the wavelength conversion characteristic of the down-conversion light-emitting particles are accurately matched, high-energy solar-blind ultraviolet light is converted into low-energy long-wave ultraviolet light capable of enabling azobenzene molecules to generate photoisomerization, an azobenzene polymer is driven to generate photoisomerization, and the light-emitting efficiency of the azobenzene polymer is improved. The film fiber network is driven to microscopically shrink and the piezoelectric polymer is excited to output an electric signal; the operation is simple and convenient, the fiber film composite material with a microstructure can be continuously manufactured in a large area, and the preparation of the large-area, fast-response and high-stability intrinsic flexible solar-blind ultraviolet detection material and the device thereof is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solar blind ultraviolet light detection materials, and particularly relates to a full-flexible solar blind ultraviolet light detection material and a preparation method and application thereof. BACKGROUND

[0002] Solar blind ultraviolet light (240-280 nm) has zero background interference and high anti-interception property in the natural environment due to the complete absorption characteristics of the earth's ozone layer, and becomes an ideal detection band in the fields of military covert communication, power equipment corona detection, etc. However, the traditional detector relies on rigid semiconductor materials such as AlGaN and ZnO, and needs high-temperature epitaxial growth (>1000℃), which leads to high preparation cost (single device cost is more than 1000 yuan) and large device brittleness (bending radius >10 mm), and it is difficult to fit the curved surface of the human body or industrial equipment, which seriously restricts its application in flexible scenarios such as wearable devices and unmanned aerial vehicle clusters.

[0003] The current industry bottleneck is concentrated in the material performance and flexibility adaptation: the mainstream material (such as ZnO) has insufficient selectivity absorption to solar blind ultraviolet light, and has significant parasitic response in the 300-400 nm band, and the signal-to-noise ratio (SNR) is generally less than 30 dB; and the flexible scheme is mostly dependent on organic semiconductors, which have poor thermal stability (<80℃) and weak environmental tolerance (performance attenuation of 50% when humidity >60%), and are difficult to meet the needs of field operations or industrial harsh environments. In addition, the prior art lacks precise control of the material component ratio (such as rare earth doping concentration fluctuation >5%), which leads to poor device consistency and insufficient yield of less than 60% in large-scale production, and breakthroughs in material system and process innovation are urgently needed.

[0004] As an emerging technology with great development potential, full-flexible electronic devices based on organic polymers are leading a new round of electronic technology revolution in the fields of information, energy, health, and national security, and have become one of the research hotspots in cross-disciplines in recent years. However, there are two major contradictions in the solar blind ultraviolet band: ① the intrinsic absorption blind area of organic materials (<300 nm) and ② the lack of flexibility of inorganic materials.

[0005] Therefore, it is of great scientific significance to expand the material system and design strategy of full-flexible solar blind ultraviolet light detection devices with intrinsic flexibility and large-area processing, and it is also a research difficulty in the field. SUMMARY

[0006] The main purpose of the present application is to overcome the defects in the prior art, and to provide a full-flexible solar blind ultraviolet light detection material and a preparation method and application thereof.

[0007] To achieve the above-mentioned purpose, the specific technical solutions are as follows: The application provides a full-flexible solar blind ultraviolet light detection material, which comprises a fiber film base body, the fiber film base body is made of a mixture of a down-conversion luminescent material, an azobenzene polymer and a piezoelectric polymer, the piezoelectric polymer is a base body, the down-conversion luminescent material is a wavelength conversion unit and emits long-wave ultraviolet under the irradiation of solar blind ultraviolet light, and the azobenzene polymer is a long-wave ultraviolet response unit.

[0008] The down-conversion luminescent material in the fiber film base body of the full-flexible solar blind ultraviolet light detection material emits long-wave ultraviolet under the excitation of solar blind ultraviolet, the emission spectrum is highly overlapped with the absorption spectrum of the azobenzene unit, and the characteristics of the down-conversion luminescent material can significantly improve the sensitivity of the material to solar blind ultraviolet by doping a small amount of the down-conversion luminescent material. The solar blind ultraviolet light is absorbed by the down-conversion luminescent material and converted into long-wave ultraviolet photons, the converted ultraviolet photons trigger the cis-trans isomerization of the azobenzene molecules, the change of the molecular configuration is conducted through the polymer network, the micro mechanical stress is accumulated, the stress can drive the carrier migration and excite the piezoelectric effect, and the conversion of the optical signal into the mechanical signal and the electrical signal is realized. When the light irradiation stops, the wavelength conversion is terminated immediately, the azobenzene molecules spontaneously restore the initial configuration, the micro deformation is reset, and the fast cyclic response capability is ensured.

[0009] Further, the down-conversion luminescent material is a rare earth doped borate, preferably, the base material of the down-conversion luminescent material is yttrium borate (YBO3), the doping element is one or more of Bi, Dy, Tm and Yb, and the molar ratio of yttrium (Y) element to doping element is 99:1-1:99, more preferably, the down-conversion luminescent material is yttrium bismuth borate (YBO3:Bi), the doping element is Bi, and the molar ratio of yttrium (Y) element to Bi is 99:1-1:99. 0.99 BO3: 0.01 Bi 3+ ).

[0010] The rare earth doped borate down-conversion luminescent material has the advantages of stable energy band structure, moderate forbidden band width, high valence band-conduction band transition efficiency and low non-radiation loss, can generate high-efficiency visible light emission under the excitation of ultraviolet or near-ultraviolet light, and is suitable for the fields of photoelectric conversion and display. The down-conversion luminescent material with yttrium borate (YBO3) as the base material and one or more of Bi, Dy, Tm and Yb as the doping element has the advantages of strong chemical stability, high optical transparency, good lattice matching, good solid solution and energy transfer effect on rare earth ions, and the like, so that the luminescent efficiency and stability of the rare earth ion activation center can be significantly improved. Especially, yttrium bismuth borate (YBO3:Bi), the Bi³⁺ ion not only can be used as a sensitizer to broaden the excitation spectrum response range and realize effective absorption on the near-ultraviolet-blue light region, but also can enhance the radiation transition efficiency of the rare earth ion through energy transfer; at the same time, the broadband emission of Bi³⁺ itself is helpful to realize the synergistic luminescence with the emission of the rare earth ion, and has unique advantages in improving the luminescent intensity of the material, improving the color purity and expanding the application waveband, and the like.

[0011] Specifically, the preparation method of the down-conversion luminescent material is that the matrix material and the doping material of the down-conversion luminescent material are sufficiently ground and mixed for 1-2 hours, and then annealed to room temperature after being reacted at 500-1000°C for 5-12 hours by high-temperature sintering method.

[0012] More preferably, the preparation method of the down-conversion luminescent material yttrium bismuth borate is that yttrium oxide (Y2O3), bismuth oxide (Bi2O3) and boric acid (H3BO3) are sufficiently ground and mixed for 1-2 hours, and then annealed to room temperature after being reacted at 500-1000°C for 5-12 hours by high-temperature sintering method; the molar ratio of the yttrium oxide (Y2O3) and the bismuth oxide (Bi2O3) is 1:99-99:1, and the total molar ratio of the boric acid (H3BO3) to the yttrium oxide (Y2O3) and the bismuth oxide (Bi2O3) is 2: (1-2).

[0013] Further, the azobenzene polymer is a succinimidyl ester functionalized azobenzene polymer; preferably, the azobenzene polymer is one or more of poly(ethylene glycol)-block-poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]undecyl methacrylate}, poly(ethylene glycol)-block-poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]hexyl methacrylate}, poly(ethylene glycol)-block-poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]ethyl methacrylate}, poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]undecyl methacrylate}, poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]hexyl methacrylate}, poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]ethyl methacrylate}; more preferably, the azobenzene polymer is poly(ethylene glycol)-block-poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]undecyl methacrylate} (CPADB-P11Az).

[0014] The succinimidyl ester functionalized azobenzene polymer can be used as a long-wave ultraviolet response unit, and has excellent photoisomerization sensitivity and modifiability. The molecule can realize fast and reversible cis-trans isomerization under ultraviolet / visible light irradiation, thereby endowing the material with potential application values such as photo-controlled switch and information storage. Meanwhile, the azobenzene polymer can form a controllable anisotropic structure under photo-induced orientation regulation, has adjustable wide-spectrum response, and can be further expanded to the visible light region through molecular design. In addition, the polymer has good chemical stability and processability, is suitable for the preparation and integration of flexible devices, and has a broad application prospect in the fields of flexible optoelectronic devices, intelligent sensors and light-driven systems due to its simultaneous light, force and electric multiple response characteristics.

[0015] Further, the preparation method of the azobenzene polymer poly(ethylene glycol)-block-poly{11-[4-(4-succinimidyl phenylazo)phenoxy]undecyl methacrylate} (CPADB-P11Az) is as follows: Poly(ethylene glycol)-block-[4-cyano-4-(thiobenzoyl)pentanoic acid] (PEO-CPADB), 11-[4-(4-succinimidyl phenylazo)phenoxy] (MA(Az-NHS)), undecyl methacrylate and azobisisobutyronitrile (AIBN) are fully dissolved and mixed in chlorobenzene solvent; After sufficient freeze-thaw operation, the mixture is placed in a 70-90℃ oil bath environment for 12h-24h to obtain azobenzene polymer poly(ethylene glycol)-block-poly{11-[4-(4-succinimidyl phenylazo)phenoxy]undecyl methacrylate} (CPADB-P11Az).

[0016] Further, the mass ratio of poly(ethylene glycol)-block-[4-cyano-4-(thiobenzoyl)pentanoic acid] (PEO-CPADB), 11-[4-(4-succinimidyl phenylazo)phenoxy] (MA(Az-NHS)), undecyl methacrylate and azobisisobutyronitrile (AIBN) is 1:(10-100):(0.1-0.5), preferably 1:40:0.2; the amount of chlorobenzene solvent used per 1mg azobisisobutyronitrile is 1ml-5ml, preferably 2.5ml.

[0017] Further, the piezoelectric polymer is selected from one or more of polyvinylidene fluoride, polyvinylidene fluoride-trifluoroethylene copolymer, polyvinylidene fluoride-hexafluoroethylene copolymer, and preferably the piezoelectric polymer is polyvinylidene fluoride-trifluoroethylene copolymer (P(VDF-TrFE)).

[0018] The piezoelectric polymer matrix simultaneously assumes the triple functions of mechanical stress conduction medium, β crystal phase piezoelectric output unit and dispersion carrier of down-conversion luminescent material. The selected piezoelectric polymer has the advantages of moderate dielectric constant, sensitive piezoelectric response and strong β crystal phase orientation, and can realize efficient electric signal output under lower stress. At the same time, this kind of polymer has excellent flexibility and stretchability, which ensures that the device still maintains stable performance under complex deformation conditions such as bending and stretching; it has good film-forming property and processing adaptability, which facilitates uniform compounding with down-conversion luminescent materials and improves the coupling efficiency of multi-physical fields of light, electricity and force. In addition, this kind of piezoelectric polymer has the characteristics of high chemical stability, light weight and large-area preparation, which provides a solid foundation for realizing flexible, integrated and wearable applications.

[0019] Further, the mass ratio of the down-conversion luminescent material to the azobenzene polymer is 1:1-1:50, preferably 1:1-1:10; and the mass ratio of the azobenzene polymer to the piezoelectric polymer is 1:1-1:5.

[0020] Within the mass ratio range, the photo-mechanical-electrical synergistic effect of the full-flexible solar blind ultraviolet light detection material of the application is further optimized.

[0021] Further, the particle size of the down-conversion luminescent material is 200-1000 nm, and the down-conversion luminescent material is surface-modified by one or more of silane coupling agent, sodium dodecyl sulfate and hexaalkyl trimethyl ammonium bromide.

[0022] In some examples, the down-conversion luminescent material is dispersed in a solvent, which is one or more of N,N-dimethylformamide (DMF), ethanol and tetrahydrofuran (THF), and is sufficiently crushed by a mortar and pestle and / or a planetary ball mill to obtain down-conversion luminescent particle material with a particle size of 200-1000 nm.

[0023] In some examples, the down-conversion luminescent material is mixed with a surfactant at a mass ratio of 45-55:1, preferably at a mass ratio of 50:1, and is sufficiently stirred at room temperature for 6-12 hours, and then is filtered, washed and dried to obtain the modified down-conversion luminescent material.

[0024] The application improves the dispersibility of the down-conversion luminescent material in the system by surface-modifying the down-conversion luminescent material.

[0025] The application further provides a preparation method of the full-flexible solar blind ultraviolet light detection material, which comprises the following steps: (1) Preparation of a base: blending a down-conversion luminescent material with an azobenzene polymer and a piezoelectric polymer base to prepare a fiber film base; (2) Cross-linking and curing: immersing the fiber film base in a cross-linking agent solution to cross-link the azobenzene polymer and form a composite fiber film; (3) Conductive treatment: sufficiently infiltrating the composite fiber film in a conductive carrier solution to complete functionalization of the composite fiber particle composite film, i.e. the full-flexible solar blind ultraviolet light detection material.

[0026] The application constructs a composite material with photo-mechanical-electrical continuous transmission function by combining the down-conversion luminescent material with the azobenzene polymer and the piezoelectric polymer, and the material has high wavelength selectivity, fast responsiveness and intrinsic flexibility and can be processed in a large area; and further, the full-flexible solar blind ultraviolet light detection material with excellent performance and stable structure is obtained, which can be further integrated into a full-flexible solar blind ultraviolet detector.

[0027] The detection process of the full-flexible solar blind ultraviolet light detection material is shown in the following figure Figure 1 The down-conversion luminescent material in the fiber particle composite film converts the solar blind ultraviolet light and stimulates the reversible isomerization reaction of the azobenzene polymer to drive the piezoelectric polymer to produce micro-deformation, causing the relative transfer of internal positive and negative charge centers to generate polarization, and driving the migration of internal conductive carriers, finally outputting the mechanical stress generated by the solar blind ultraviolet light in the form of an electric signal. In summary, the solar blind ultraviolet light is converted in wavelength by the down-conversion particle, triggering the reversible isomerization of the azobenzene → driving the micro-deformation of the piezoelectric polymer → inducing the polarization of the internal charge and the migration of the carrier → forming a bound charge on the surface of the material → outputting an electric signal.

[0028] Further, the cross-linking agent is an active amino cross-linking agent, preferably one or more of polyamine macromolecular compounds with a molecular weight of 600-70,000 g / mol; the concentration of the cross-linking agent solution is 1-10 mg / ml, preferably 0.5-3 mg / mL.

[0029] The multi-amino cross-linking agent and the active succinimidyl ester group at the end of the side chain of the azobenzene polymer can undergo a high-efficiency nucleophilic substitution reaction at room temperature to form a moderately cross-linked liquid crystal elastomer network.

[0030] Further, the conductive carrier is selected from one or more of carbon nanotubes, ionic liquids, silver nanowires, and reduced graphene oxide, and the concentration of the conductive carrier solution is 90-99%, preferably the concentration of the conductive carrier solution is 99%.

[0031] Further, the fiber film matrix is prepared by a spinning method or a 3D printing method; wherein the spinning method is selected from one of solution spinning, melt spinning, phase separation spinning, jet spinning, electrospinning, and microfluidic spinning; preferably electrospinning, the electrospinning process realizes the high orientation arrangement of azobenzene units and the deep embedding of down-conversion luminescent material particles, the spontaneous phase transition of piezoelectric polymer α→β (without subsequent polarization), and obtains a large-area, washable, stretchable and foldable high-breathable film.

[0032] Specifically, in the electrospinning process, the positive direct current voltage is 8-20 kV, and the negative direct current voltage is -3 to -10 kV; the volume of the solution in the syringe is 0.5-5 mL, and the solution advancing speed in the syringe is 0.5-2 mL / h; the receiving device is a flat plate or a drum with a layer of aluminum foil pasted on the surface, and the rotating speed of the drum is 50-3000 rpm; the distance between the needle and the receiving device is 5-15 cm; the mixed solution is continuously electrospun to obtain a fiber film with a thickness of 10-150 μm. After spinning, the fiber film can be torn off with a pointed forceps and cut into any shape and size with surgical scissors.

[0033] Further, in step (2), the fiber film matrix is soaked in the crosslinking agent solution for 3-12 hours.

[0034] Further, in step (3), the composite fiber film is soaked in the conductive carrier solution for 12-24 hours.

[0035] In one embodiment of the present application, the preparation method of the full-flexible solar blind ultraviolet detection material comprises the following steps: 1) Surface-modified down-conversion luminescent particles with a particle size of 200-1000 nm are mixed with succinimidyl functionalized azobenzene polymer and piezoelectric polymer and dissolved in a cosolvent, ultrasonic dispersion is performed for 30-60 min, and a magnetic stirrer is used for stirring at 35-45 DEG C for 6-12 hours to fully disperse to form a uniform viscous solution, and a fiber film matrix is prepared by a spinning method; 2) An active amino crosslinking agent is dissolved in a solvent to form a dispersion with a concentration of 0.5-3 mg / mL, the fiber film matrix is immersed in the dispersion for crosslinking reaction for 6-12 hours, the succinimide groups and the polyamine groups are constructed into a covalent crosslinking network through a nucleophilic substitution reaction, the film is taken out and cleaned with a solvent to remove free crosslinking agents, and the composite fiber film is obtained after ventilation and drying; 3) The composite fiber film is placed in a conductive carrier solution for penetration treatment, the surface residual liquid is absorbed and removed after taking out, and the full-flexible solar blind ultraviolet detection material is obtained after drying; the conductive carrier solution is one or more of an ionic liquid [EMIm][TFSI], a carbon nanotube aqueous dispersion, or a silver nanowire ethanol dispersion.

[0036] The present application also provides a full-flexible solar blind ultraviolet light detector comprising the full-flexible solar blind ultraviolet light detection material or the full-flexible solar blind ultraviolet light detection material prepared by the preparation method.

[0037] For example, the assembly of the full-flexible solar blind detection device is completed by laminating a flexible cloth electrode on the lower surface of the full-flexible solar blind ultraviolet detection material and welding copper lead wires on the upper and lower surfaces.

[0038] The present application also provides applications of the full-flexible solar blind ultraviolet light material or the full-flexible solar blind ultraviolet light detector in the preparation of power equipment corona detection, military covert communication, unmanned aerial vehicle cluster monitoring-solar blind ultraviolet intensity monitoring, ultraviolet communication, light source positioning, and wearable devices.

[0039] For example, the full-flexible solar blind ultraviolet light material or the full-flexible solar blind ultraviolet light detector is used to prepare a wireless transmission system that can monitor the solar blind ultraviolet intensity in real time.

[0040] For another example, the full-flexible solar blind ultraviolet light detector forms a signal transmission system by being connected with a signal amplifier, accesses an Arduino microcontroller, connects a Bluetooth module, and is made into visual software for receiving and displaying Bluetooth transmission information, so that the current measurement result can be wirelessly transmitted to a visual device.

[0041] Compared with the prior art, the present application has the following remarkable beneficial effects: The full-flexible solar blind ultraviolet light detection material provided by the present application utilizes the wavelength conversion characteristics of the down-conversion luminescent material to convert high-energy solar blind ultraviolet light into low-energy long-wave ultraviolet light that can cause the photoisomerization of azobenzene molecules, that is, the response wavelength of the low-energy long-wave ultraviolet light of the azobenzene group which is not sensitive to solar blind ultraviolet light is blue-shifted to the high-energy short-wave solar blind ultraviolet region, and then under the irradiation of solar blind ultraviolet light, the photoisomerization reaction of the azobenzene group can still be realized, and the dynamic disorder of the molecular shape drives the micro-shrinkage of the fiber network of the thin film, exciting the piezoelectric polymer to output a macro-voltage signal, which can be amplified and detected by an electrometer to realize the detection of the intensity of solar blind ultraviolet light.

[0042] The present application innovatively constructs a three-stage cascade response system aiming at the zero-background interference characteristics of solar blind ultraviolet light and the intrinsic flexible detection demand: ① Rare earth doped down-conversion luminescent material realizes 240~280nm→300~400nm spectral conversion; ② Wavelength adapted azobenzene liquid crystal elastomer triggers rapid isomerization (response time 90ms); ③ Piezoelectric matrix synchronously converts mechanical stress / carrier migration into electrical signal output.

[0043] The present application bridges the advantages of organic and inorganic materials through down-conversion luminescent material, and comprehensively utilizes the material characteristics of each part, compared with rigid semiconductor devices, the present application relies on the solution processing of polymer materials, and has the advantages of large-area manufacturing, low cost and dynamic environmental stability, and the organic-inorganic composite structure of the present application breaks through the bottleneck of curved surface fitting of traditional semiconductor detectors.

[0044] The present application can continuously manufacture fiber thin film composite materials with microstructure in a simple and easy-to-operate manner, and construct a multi-stage signal transmission mechanism of "solar blind ultraviolet→wavelength conversion→photoisomerization→mechanical deformation→electrical signal output", so that the preparation of large-area, fast-response and high-stability intrinsic flexible solar blind ultraviolet detection material and devices is realized. Further integrating Internet of Things technology (such as Arduino single-chip microcomputer+Bluetooth module), an intelligent sensing system applied to military covert communication, power equipment corona monitoring, unmanned aerial vehicle cluster positioning and other scenes can be developed. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0046] Figure 1 is a detection process schematic diagram of the solar blind ultraviolet monitoring of the solar blind ultraviolet light detection material of the present application; Figure 2 is the excitation spectrum of the down-conversion luminescent material yttrium bismuth borate (Y 0.99 BO3: 0.01 Bi 3+ ) prepared by the present application and the ultraviolet-visible spectrum of azobenzene polymer CPADB-P11Az; Figure 3 is the molecular structure of the azobenzene polymer, the cross-linking agent polyimide and the conductive carrier ionic liquid in Example 1 of the present application; Figure 4 is the high-resolution scanning electron microscope (SEM) photograph of the surface of the original full-flexible solar blind ultraviolet light detection material and the surface of the full-flexible solar blind ultraviolet light detection material after spin-coating of silver nanowire ethanol solution in Example 1 of the present application; Left graph: the surface of the original full-flexible solar blind ultraviolet light detection material; Right graph: the surface of the full-flexible solar blind ultraviolet light detection material after spin-coating of silver nanowire ethanol solution; Figure 5 is the short-circuit current-time curve of the full-flexible solar blind ultraviolet light detector under irradiation of solar blind ultraviolet light with different intensities in Application Example 1 of the present application; Figure 6 is the open-circuit voltage-time curve of the full-flexible solar blind ultraviolet light detector under irradiation of solar blind ultraviolet light with different intensities in Application Example 1 of the present application; Figure 7 is a photograph of the wireless monitoring solar blind ultraviolet light intensity sensor in Application Example 2 of the present application; Left graph: solar blind ultraviolet monitoring system; Right graph: real-time monitoring of solar blind light intensity and realization of digital output of intensity value. DETAILED DESCRIPTION

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0048] In this invention, all instruments and other equipment whose manufacturers are not specified are conventional products that can be purchased through legitimate channels. Unless otherwise specified, all methods described are conventional methods, and all raw materials are commercially available. Where specific techniques or conditions are not specified in the embodiments, they should be performed in accordance with the techniques or conditions described in the literature in this field, or according to the product instructions.

[0049] Preparation of surface-modified downconversion luminescent material particles: 1. Preparation of downconversion luminescent materials by high-temperature solid-state reaction method: 1.10 g of yttrium oxide (Y₂O₃), 0.023 g of bismuth oxide (Bi₂O₃), and 0.618 g of boric acid (H₃BO₃) were weighed sequentially into an agate mortar and ground for 2 hours until the powder was uniformly mixed. The ground powder was transferred to a crucible, which was then placed in a tube furnace and calcined at 1000 °C in air atmosphere for 10 hours, followed by annealing to room temperature. The calcined lumps were further ground into a fine powder using a planetary ball mill to obtain yttrium bismuth borate (Y₂O₃) downconversion luminescent material with a particle size of approximately 500 nm. 0.99 BO3: 0.01 Bi 3+ )powder.

[0050] 2. Surface modification of downconversion luminescent materials: Yttrium bismuth borate (Y 0.99 BO3: 0.01 Bi 3+ The powder was added to a silane coupling agent (KH550) and stirred thoroughly overnight. After washing with ethanol, filtering, and drying, surface-modified downconversion luminescent particles were obtained. Surface-modified yttrium borate (YB) bismuth borate was then obtained. 0.99 BO3: 0.01 Bi 3+ ).

[0051] Figure 2 Yttrium bismuth borate (YBB) is a downconversion luminescent material. 0.99 BO3: 0.01 Bi 3+ The excitation spectrum at 275 nm and the UV-Vis absorption spectrum of the azobenzene polymer CPADB-P11Az show that their wavelength ranges overlap to a large extent.

[0052] The preparation method of azobenzene polymer poly(ethylene glycol)-block-poly{11-[4-(4-succinimidyl phenylazo) phenoxy]undecyl methacrylate} (CPADB-P11Az) (molecular structure as shown in Figure 3 is as follows: 68.87 mg of poly(ethylene glycol)-block-[4-cyano-4-(thiobenzoyl) pentanoic acid] (PEO-CPADB) and 1.054 g of 11-[4-(4-succinimidyl phenylazo) phenoxy] (MA(Az-NHS)) and 1 mg of azobisisobutyronitrile (AIBN) are weighed and dissolved in 2.5 ml of chlorobenzene solvent to mix; the mixture is subjected to sufficient freeze-thaw operation, placed in a 80°C oil bath environment under vacuum for 20 h to obtain azobenzene polymer poly(ethylene glycol)-block-poly{11-[4-(4-succinimidyl phenylazo) phenoxy]undecyl methacrylate} (CPADB-P11Az).

[0053] The above-prepared substance is used in the following examples.

[0054] Example 1 The present example provides a preparation method of a full-flexible solar blind ultraviolet detection material, and the specific preparation method is as follows: (1) Preparation of the substrate: 300 mg of poly(vinylidene fluoride-trifluoroethylene) copolymer (P(VDF-TrFE)) pellets, 100 mg of azobenzene polymer (CPADB-P11Az) powder and 20 mg of surface-modified Y 0.99 BO3: 0.01 Bi 3+ particles are blended to prepare a fiber thin film substrate; The preparation of the fiber thin film substrate in the present example adopts an electrospinning process: 300 mg of poly(vinylidene fluoride-trifluoroethylene) copolymer (P(VDF-TrFE)) pellets and 100 mg of azobenzene polymer (CPADB-P11Az) powder are placed in a glass bottle, 1 mL of N,N-dimethylformamide (DMF) and 1 mL of tetrahydrofuran (THF) mixed solvent are added. A heat collecting magnetic stirrer is used for continuous stirring at 40°C for 6 hours until a uniform solution is formed. 20 mg of surface-modified Y 0.99 BO3: 0.01 Bi 3+ particles are added, ultrasonic treatment is performed for 30 minutes, and then magnetic stirring is performed for 3 hours to achieve uniform distribution of the particles in the polymer matrix.

[0055] The blended solution was injected into a 5 mL syringe and spun under the following parameters: DC voltage: 12 kV, solution push rate: 1 mL / h, needle-receiver distance: 15 cm, drum receiver rotation speed: 3000 rpm (surface covered with 50 x 200 mm aluminum foil), spinning continued until 1 mL of solution was exhausted, obtaining a fiber film matrix of target thickness ~ 25 μιη. The fiber film matrix was torn off, dried overnight at room temperature, and cut into 25 x 15 mm samples for later use.

[0056] (2) Cross-linking and curing: A cross-linking solution of 2 mg / ml was prepared using polyethyleneimine with molecular weight of 10000 g / mol (molecular structure as shown in Figure 3 ) and anhydrous ethanol, and the solution was ultrasonicated for 30 min and stirred until the polyethyleneimine was completely dissolved and a uniform transparent solution was formed. The cut film sample was immersed in the cross-linking solution for 6 hours, so that the active ester groups of the azobenzene polymer were fully cross-linked with the imine bond, and the down-conversion luminescent particles were firmly fixed on the fiber. After the fiber film was taken out, it was washed with anhydrous ethanol to remove the residual cross-linking solution on the surface, and then dried in a vacuum oven at 45°C for 2 hours to obtain a slightly cross-linked fiber film; (3) Conductive treatment: The dried slightly cross-linked fiber film was placed in a 99% ionic liquid ([EMIm][TFSI]) (structure as shown in Figure 3 ) solution at room temperature for 6 hours, so that the conductive particles were fully filled in the fiber gap. After taking out, the surface residual ionic liquid was removed with filter paper to obtain a fiber film with certain mechanical strength, i.e. a full-flexible solar blind ultraviolet detection material.

[0057] Example 2 The preparation method of this example is basically the same as that of Example 1, the only difference being that the surface-modified Y 0.99 BO3: 0.01 Bi 3+ particles with a weight of 10 mg were used.

[0058] Example 3 The preparation method of this example is basically the same as that of Example 1, the only difference being that the surface-modified Y 0.99 BO 3:0.01 Bi 3+ particles with a weight of 100 mg were used.

[0059] The full-flexible solar blind ultraviolet detection materials prepared in Examples 1-3 were subjected to solar blind ultraviolet irradiation and the short-circuit current change was tested using an electrometer, and the linear regression analysis of the ultraviolet light intensity and the short-circuit current change value was performed. The test results are shown in Table 1 below, and the short-circuit current change was selected at 45 mW / cm 2 of solar blind ultraviolet light intensity.

[0060] Table 1 Test Results

[0061] As can be seen from the data in Table 1, the fully flexible solar-blind ultraviolet detector materials prepared in Examples 1-3 of this invention can successfully convert solar-blind ultraviolet light into electrical signal output, and the downconversion particles Y 0.99 BO3: 0.01 Bi 3+ Different doping contents have a large effect on the change value of photocurrent and the linear correlation between current and light intensity. In Example 2, the conversion efficiency is low and the change value of photocurrent is small with low doping content, while the linear correlation is high. In Example 3, the conversion efficiency is high with high doping content, the change value of photocurrent is large and the linear correlation is low. The above examples cannot be effectively applied. Therefore, Example 1 is preferred, which ensures a high change value of photocurrent while ensuring a high linear correlation.

[0062] Application Example 1: This embodiment provides a method for integrating and encapsulating the fully flexible solar-blind ultraviolet detection material prepared in Example 1 into a fully flexible solar-blind ultraviolet detector. The intensity of solar-blind ultraviolet light is characterized by the change in electrical signal generated at both ends of the digital meter detection device under solar-blind ultraviolet light irradiation. The specific steps are as follows: 1) Fabrication of a fully flexible solar-blind ultraviolet detector: A sample of the fully flexible solar-blind ultraviolet detector material prepared in Example 1 was used. Copper wires were soldered to the edge of any one side using conductive silver paste. Simultaneously, a flexible single-sided conductive cloth electrode was completely adhered to that side. Then, a transparent conductive silver nanowire electrode was spin-coated onto the other side using a spin coater. The silver nanowires were prepared using a 1 wt.% aqueous dispersion, mixed with anhydrous ethanol at a volume ratio of 1:2. 500 μL of this mixture was spin-coated to form a transparent electrode with a surface resistivity of 20–50 Ω. Figure 4 Scanning electron microscopy revealed that the highly oriented nanofibers exhibited a neat axial arrangement, with downconversion luminescent particles adhering to the fiber surface. Silver nanowires overlapped between the fibers to form a complete conductive network. A copper wire was then soldered onto the edge of the transparent electrode surface using conductive silver paste, with this wire and the other copper wire distributed on opposite sides of the fiber membrane. After the conductive silver paste had fully dried in air, the copper wire bonding locations were sealed using an adhesive-coated glass plate, resulting in a fully flexible solar-blind ultraviolet detector.

[0063] 2) Detection of changes in electrical signals after the device is exposed to solar-blind ultraviolet light: The solar blind ultraviolet light uses a 275nm wavelength light source, with a maximum light intensity of 75mW / cm². 2, the digital multimeter is used for detecting the change of the electrical signal of the blind ultraviolet detection device, and the detection system is composed of a Keithley 6517B and accessories thereof and a computer loaded with a matching software. The lead wire of the full-flexible blind ultraviolet detector prepared in the previous step is connected to the positive and negative interfaces of the digital multimeter, and when the blind ultraviolet light source with different light intensities irradiates the device, the electrical signal of the device is presented on the computer screen in real time by the digital multimeter, and the data of the current, voltage, irradiation time, blind ultraviolet light intensity and the like are exported, and the linear regression method is used to fit the corresponding relationship between the electrical signal and the light intensity and obtain a linear fitting curve. Figures 5-6 The full-flexible blind ultraviolet light detector is a short-circuit current and open-circuit voltage-time curve under different light intensities. It can be seen that under the condition that the light intensity of the blind ultraviolet light source is limited, the device can detect a light intensity as low as 11 mW / cm 2 The current response time is 90 ms, the voltage response time is 40 ms, and the electrical signal has a good linear corresponding relationship with the light intensity. As can be seen from the above, the full-flexible blind ultraviolet detector of the application has a low detection limit, a fast response, an excellent and stable performance, and can meet the application in the fields of blind ultraviolet monitoring and non-line-of-sight ultraviolet communication.

[0064] Application Example 2 The embodiment provides a blind ultraviolet light monitoring system, which comprises the full-flexible blind ultraviolet detector in the embodiment 2, a 275 nm blind ultraviolet light source, a voltage amplifier and a matching direct current power supply, an Arduino microcontroller circuit and a Bluetooth module, a notebook computer and an electronic display device receiving a signal, and the specific implementation steps are as follows: The full-flexible blind ultraviolet detector is connected to the Arduino microcontroller in the circuit connection mode of the voltammetry method, and when the blind ultraviolet light source with unknown intensity irradiates the device, the electrical signal is output by the device, the electrical signal is introduced into the Arduino microcontroller through the voltage amplifier and is recognized, and the current blind light intensity is output on the electronic display device receiving a signal through the Bluetooth module. The principle is that according to the linear regression curve of the electrical signal-light intensity in the embodiment 2, the voltage value loaded on the device is read by the analog pin of the Arduino to deduce the light intensity value, so that the real-time monitoring of the light intensity is realized.

[0065] The blind ultraviolet light monitoring system described in the embodiment is like Figure 7As shown, it comprises a light source controller, a photodetector, a voltage amplifier, a Bluetooth, and an Arduino single-chip microcomputer, wherein the light source controller provides the 275nm wavelength light in the solar blind region, the photodetector is used for converting the solar blind ultraviolet light signal into an electric signal, the voltage amplifier is used for amplifying the electric signal output by the photodetector and inputting into the Arduino single-chip microcomputer, and through computer programming, the amplified light response signal is converted into the corresponding solar blind ultraviolet light intensity.

[0066] When irradiated by the light intensity of 75mW / cm -2 , the electronic display device displays the solar blind ultraviolet light intensity as "74.8mW / cm -2 ", indicating that the detection precision is good.

[0067] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A full-flexible solar blind ultraviolet photodetector material, characterized in that, The fiber film matrix is prepared from a mixture of down-conversion luminescent material, azobenzene polymer and piezoelectric polymer; the piezoelectric polymer is the matrix; the down-conversion luminescent material is a wavelength conversion unit, emitting long-wave ultraviolet under solar blind ultraviolet irradiation; and the azobenzene polymer is a long-wave ultraviolet response unit. 2.The full-flexible solar blind ultraviolet photodetector material of claim 1, wherein, The down-conversion luminescent material is a rare earth doped borate; preferably, the matrix material of the down-conversion luminescent material is yttrium borate, and the doping element is one or more of Bi, Dy, Tm and Yb, and the molar ratio of yttrium element to doping element is 99:1-1:99; more preferably, the down-conversion luminescent material is yttrium bismuth borate. 3.The full-flexible solar blind ultraviolet photodetector material according to claim 1 or 2, characterized in that, The azobenzene polymer is succinimidyl-functionalized azobenzene polymer; preferably, the azobenzene polymer is one or more of poly(ethylene glycol)-block-poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]undecyl methacrylate}, poly(ethylene glycol)-block-poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]hexyl methacrylate}, poly(ethylene glycol)-block-poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]ethyl methacrylate}, poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]undecyl methacrylate}, poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]hexyl methacrylate}, and poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]ethyl methacrylate}; more preferably, the azobenzene polymer is poly(ethylene glycol)-block-poly{11-[4-(4'-succinimidyl phenylazo)phenoxy]undecyl methacrylate}. 4.The full-flexible solar blind ultraviolet photodetector material of claim 3, wherein, The piezoelectric polymer is selected from one or more of polyvinylidene fluoride, polyvinylidene fluoride-trifluoroethylene copolymer and polyvinylidene fluoride-hexafluoroethylene copolymer; preferably, the piezoelectric polymer is polyvinylidene fluoride-trifluoroethylene copolymer. 5.The full-flexible solar blind ultraviolet photodetector material according to claim 1 or 2 or 4, characterized in that, The mass ratio of the down-conversion luminescent material to the azobenzene polymer is 1:1-1:50, and the mass ratio of the azobenzene polymer to the piezoelectric polymer is 1:1-1:5; preferably, the mass ratio of the down-conversion luminescent material to the azobenzene polymer is 1:1-1:

10. 6.The full-flexible solar blind ultraviolet photodetector material according to claim 1 or 2 or 4, characterized in that, The particle size of the down-conversion luminescent material is 200-1000 nm, and the down-conversion luminescent material is surface-modified by one or more of silane coupling agent, sodium dodecyl sulfate and hexaalkyltrimethylammonium bromide.

7. A method for preparing the full-flexible solar blind ultraviolet photodetector material according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: (1) Matrix preparation: blending down-conversion luminescent material with azobenzene polymer and piezoelectric polymer matrix to prepare a fiber film matrix; (2) Cross-linking and curing: soaking the fiber film matrix in a cross-linking agent solution to cross-link the azobenzene polymer and form a composite fiber film; (3) Conductive treatment: fully infiltrating the composite fiber film in a conductive carrier solution to complete functionalization of the composite fiber particle composite film, i.e. a full-flexible solar blind ultraviolet light detection material. 8.The method of claim 7, wherein the method further comprises the step of: coating the photoconductive layer with a transparent conductive layer. The cross-linking agent is an active amino cross-linking agent, preferably one or more of polyamine macromolecular compounds with a molecular weight of 600-70000 g / mol; the cross-linking agent solution concentration is 1-10 mg / ml, preferably 0.5-3 mg / mL; And / or, the conductive carrier is selected from one or several of carbon nanotubes, ionic liquids, silver nanowires, reduced graphene oxide, and the conductive carrier solution concentration is 90-99%, preferably, the conductive carrier solution concentration is 99%. 9.A full-flexible solar blind ultraviolet photodetector comprising the full-flexible solar blind ultraviolet photodetector material of any one of claims 1 to 6 or the full-flexible solar blind ultraviolet photodetector material obtained by the method of any one of claims 7 or 8. 10.The use of the full-flexible solar blind ultraviolet photodetector material of any one of claims 1 to 6 or the full-flexible solar blind ultraviolet photodetector of claim 9 in the preparation of power equipment corona detection, military covert communication, unmanned aerial vehicle cluster monitoring-solar blind ultraviolet intensity monitoring, ultraviolet communication, light source positioning, wearable devices.

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