Stretchable high-energy photodetector based on perovskite quantum dot film

Abstract

The application discloses a stretchable high-energy light detector based on a perovskite quantum dot film. The detector comprises, from bottom to top, a stretchable substrate, a stretchable gate electrode, a stretchable insulating layer, a stretchable polymer semiconductor layer, a stretchable van der waals heterojunction source-drain electrode and a photosensitive layer. The stretchable high-energy light detector is of a bottom gate top contact structure, and the photosensitive layer is made of perovskite quantum dots with high absorption efficiency, high photoluminescence quantum efficiency and long exciton diffusion length. The application proposes a strategy of surface energy-induced self-assembly of perovskite quantum dots, prepares a uniform, compactly arranged, easily transferred and flexible worm-like perovskite quantum dot film, and realizes the application of a high-crystalline granular perovskite quantum dot film in a stretchable photoelectric detector.

Description

Technical Field

[0001] This invention belongs to the field of flexible photoelectric detection technology, specifically relating to a method for surface energy-induced self-assembly of perovskite quantum dots, and a structure of a high-performance stretchable high-energy photodetector. Background Technology

[0002] Flexible and stretchable electronic devices possess mechanical properties similar to human skin, enabling them to seamlessly attach to irregular, curved, and moving objects. Given this, stretchable electronic devices have shown great potential in fields such as physiological monitoring, medical diagnostics, medical implantation, human-computer interaction, flexible robotics, and augmented reality ((a) Tee, BCK; Chortos, A.; Berndt, A.; et al. Science 2015, 350, 313. (b) Kang, SK; Murphy, RKJ; Hwang, SW; et al. Nature 2016, 530, 71. (c) Lim, S.; Son, D.; Kim, J.; et al. Advanced Functional Materials 2015, 25, 375.). Thanks to the continuous efforts of researchers, most stretchable electronic devices, including stretchable transistors, stretchable light-emitting diodes, stretchable energy storage and conversion devices, stretchable sensors, and stretchable memories, have been realized and exhibit excellent electrical performance and ideal tensile strain resistance. However, due to the lack of suitable photosensitive materials and device fabrication technologies, intrinsically stretchable phototransistors have not yet been successfully fabricated, and are therefore considered a significant shortcoming in the wearable electronics market.

[0003] Based on their device structure, photodetectors mainly include phototransistors, photodiodes, and photoconductors. Compared to photodiodes and photoconductors, phototransistors (PTs) have advantages such as high sensitivity, low noise, integration of light detection and signal amplification functions, and convenient circuit integration (Chinese Patent 201810746339.4). Therefore, phototransistors are not only preferred device prototypes for studying the photoelectric properties of specific materials, but also hold promise for realizing photoelectric sensors. Among all photosensitive materials, perovskite quantum dots are widely used in photodetectors due to their high absorption efficiency, high photoluminescence quantum efficiency, long exciton diffusion length, and size-tunable bandgap. However, currently reported perovskite quantum dot films are difficult to apply to the field of stretchable optoelectronics due to their dense nanocrystals and highly crystalline structure. Therefore, how to fabricate high-performance stretchable phototransistors using appropriate methods, and how to apply traditional highly crystalline perovskite quantum dot films to the field of stretchable photodetectors, are two very significant challenges. Summary of the Invention

[0004] In view of the shortcomings of the prior art, one object of the present invention is to provide a method for surface energy-induced self-assembly of perovskite quantum dots, so as to achieve effective control over the morphology and elasticity of perovskite quantum dot films, and aim to prepare a uniform, compactly arranged, easily transferable and flexible worm-like perovskite quantum dot film.

[0005] The method for surface energy-induced self-assembly of perovskite quantum dots provided by the present invention includes the following steps: using perovskite quantum dot dispersion as raw material, a solution deposition method is used to prepare a worm-like perovskite quantum dot film on a surface-hydroxylated polydimethylsiloxane plate;

[0006] The perovskite quantum dots are selected from perovskite quantum dots with high absorption efficiency, high photoluminescence quantum efficiency, and long exciton diffusion length, such as CsPbBr3 and CsPbI3 quantum dots.

[0007] The concentration of perovskite quantum dots in the perovskite quantum dot dispersion is 5–15 mg / mL, and the dispersion medium is selected from any one of toluene, cyclohexane, cyclopentane, and n-hexane;

[0008] The solution deposition method includes any one of the following: drop coating, spin coating, blade coating, roller coating, brush coating, and stretch coating;

[0009] The thickness of the worm-like perovskite quantum dot film can be 50-200 nm.

[0010] The above preparation method further includes: after preparation, annealing the substrate with the thin film on its surface, wherein the annealing conditions are: annealing at 40-80°C for 1-10 minutes on a hot table, specifically annealing at 60°C for 5 minutes on a hot table.

[0011] In the above preparation method, the surface-hydroxylated polydimethylsiloxane plate is obtained by ultraviolet ozonolysis of the polydimethylsiloxane plate; the ultraviolet ozonolysis treatment time is 5-20 minutes.

[0012] The worm-like perovskite quantum dot films prepared by the above method are also within the scope of protection of this invention.

[0013] Another objective of this invention is to provide a novel, high-performance, intrinsically stretchable high-energy photodetector based on perovskite quantum dot thin films, which is stable under high mechanical deformation.

[0014] The stretchable high-energy photodetector based on perovskite quantum dot thin film provided by the present invention comprises, from bottom to top, a stretchable substrate, a stretchable gate electrode, a stretchable insulating layer, a stretchable polymer semiconductor layer, a stretchable van der Waals heterojunction source and a drain electrode located on the same plane, and a photosensitive layer located in the channel formed by the stretchable van der Waals heterojunction source and the drain electrode.

[0015] The stretchable high-energy photodetector has a bottom grid top contact structure.

[0016] In the aforementioned stretchable high-energy photodetector, the high-energy light is high-energy photons, including ultraviolet light, X-rays, or gamma rays.

[0017] In the aforementioned stretchable high-energy photodetector, the photosensitive layer is a worm-like perovskite quantum dot film.

[0018] In the aforementioned stretchable high-energy photodetector, the stretchable polymer semiconductor layer is made of a stretchable organic semiconductor blend system;

[0019] The stretchable organic semiconductor blend system is prepared by solution blending of a conjugated polymer and an elastomer polymer.

[0020] The conjugated polymer is selected from any one of poly(2,5-bis(2-octyldodecyl)-3,6-bis(thiophen-2-yl)dionepyrrole[3,4-c]pyrrole-1,4-dione-alt-thiophene[3,2-b]thiophene)(DPPT-TT), poly[(2,5-bis(5-decyl-1-pentyl)–3,6-bis(thiophen-2-yl)pyrrole[3,4-c]pyrrole-1,4(2H,5H)-dione)-alt-((E)–1,2-bis(thiophen-2-yl)ethane], poly(2,5-bis(3-alkylthiophene-2-yl)thiophene[3,2-b]thiophene(PBTTT), poly(tetrathiopheneacetic acid dionepyrrole))(PTDPPTFT4), polyisoindigodithiophene(PII2T), and poly(3-hexylthiophene))(P3HT);

[0021] The elastomer polymer is any one of hydrogenated styrene-butadiene block copolymer (SEBS), polydimethylsiloxane (PDMS), natural rubber (NR), styrene-butadiene rubber (SBR), ethylene propylene rubber (EPR), butyl rubber (IIR), and polyurethane elastomer (PU);

[0022] The blending mass ratio of the conjugated polymer to the elastomer polymer is 1-9:1-9 (specifically, 1:1);

[0023] The solvent used in the solution blending method is any one of chlorobenzene, o-dichlorobenzene, toluene, and xylene;

[0024] The solution blending conditions are as follows: stirring temperature 50-100℃, stirring speed 100-1000 rpm; stirring time 0.5-5 hours.

[0025] The thickness of the stretchable polymer semiconductor layer can be 50-150 nm, preferably 60-90 nm.

[0026] In the aforementioned stretchable high-energy photodetector, both the stretchable substrate and the stretchable insulating layer are made of elastomeric polymers via a solution method.

[0027] The elastomer polymer is selected from any one of polydimethylsiloxane (PDMS), hydrogenated styrene-butadiene block copolymer (SEBS), styrene-butadiene rubber (SBR), natural rubber (NR), ethylene propylene rubber (EPR), butyl rubber (IIR), and thermoplastic polyurethane elastomer (PU);

[0028] The solvent used in the solution method is any one of toluene, xylene, chlorobenzene, cyclohexane, and n-hexane;

[0029] The thickness of the stretchable substrate is 200μm-3mm, preferably 500μm-1.5mm;

[0030] The thickness of the stretchable insulating layer is 1-3 μm, preferably 1-1.5 μm.

[0031] The aforementioned stretchable high-energy photodetector has a stretchable van der Waals heterojunction source and drain electrode that are parallel heterojunction structures composed of single-walled carbon nanotubes and small organic molecules.

[0032] The single-walled carbon nanotubes include any one of P2-SWNT, P3-SWNT, P5-SWNT, P7-SWNT, P8-SWNT, and P9-SWNT;

[0033] The organic small molecules include any one of tetraphenyl, pentaphenyl, copper phthalocyanine, vanadium titanyl cyanocyanate, rubrene, pentathiazole and PCBM;

[0034] The organic small molecules are deposited on the surface of the single-walled carbon nanotube electrode by vacuum evaporation.

[0035] The vacuum evaporation conditions are: a vacuum degree of 10. -4 -10 -6 Pascal, evaporation rate is 1-5 angstroms / second.

[0036] The thickness of the organic small molecule layer is 10-60 nm, preferably 20-40 nm.

[0037] In the aforementioned stretchable high-energy photodetector, the stretchable gate electrode is fabricated from carbon nanotubes;

[0038] The carbon nanotubes are single-walled carbon nanotubes, including any one of P2-SWNT, P3-SWNT, P5-SWNT, P8-SWNT, and P9-SWNT.

[0039] The method for preparing the above-mentioned stretchable high-energy photodetector provided by the present invention includes the following steps:

[0040] 1) The stretchable substrate, the stretchable gate electrode, the stretchable insulating layer, the stretchable polymer semiconductor layer, the stretchable van der Waals heterojunction source, and the drain electrode are respectively fabricated on a substrate with a self-assembled molecular layer;

[0041] 2) The photosensitive layer is prepared on a surface-hydroxylated polydimethylsiloxane plate;

[0042] 3) Using pointed tweezers, transfer the stretchable substrate from the substrate with the self-assembled molecular layer, and then gently cover the stretchable gate electrode from one side; transfer the stretchable gate electrode to the stretchable substrate by thermal bonding; then, using the same method and steps, sequentially transfer the stretchable insulating layer, the stretchable polymer semiconductor layer, and the stretchable van der Waals source and drain electrodes located on the same plane to the stretchable gate electrode; finally, transfer the photosensitive layer from the surface-hydroxylated polydimethylsiloxane plate to the channel of the stretchable van der Waals heterojunction source and drain electrodes to obtain a stretchable high-energy photodetector based on perovskite quantum dot thin film.

[0043] In the above preparation steps, the substrate with the self-assembled molecular layer is made of any one of silicon wafer, glass, ceramic, metal, quartz and hard alloy;

[0044] Before use, the substrate is ultrasonically cleaned with detergent, deionized water, acetone and ethanol in sequence, dried with a nitrogen gun, and then subjected to ultraviolet peroxidation (UVO) treatment to obtain a clean substrate.

[0045] The conditions for the ultrasound are: ultrasound power of 10-100 watts; ultrasound time of 1-30 minutes; ultrasound frequency of 10-100 kilohertz.

[0046] The conditions for the ultraviolet peroxidation treatment are: treatment time of 10-30 minutes.

[0047] The aforementioned substrate with a self-assembled molecular layer is prepared by heating or immersing the clean substrate in a solution under vacuum conditions with any one of octadecyltrimethoxysilane, octadecyltrichlorosilane, octadecyltrichlorosilane, and phenyltrichlorosilane.

[0048] The conditions for the vacuum heating treatment are: vacuum degree of 0.1 Pascal, heating temperature of 50-150℃, and heating time of 1-5 hours.

[0049] The conditions for immersion treatment in the solution are as follows: the solvent used is any one of n-hexane, n-heptane, and cyclohexane; the volume ratio of any one of octadecyltrimethoxysilane, octadecyltrichlorosilane, octadecyltrichlorosilane, or phenyltrichlorosilane to n-hexane, n-heptane, isohexane, or cyclohexane is 1:200-1:1000, and the immersion time is 0.1-3 hours.

[0050] In the above preparation steps, the surface-hydroxylated polydimethylsiloxane plate is obtained by ultraviolet ozonolysis of the polydimethylsiloxane plate;

[0051] The ultraviolet ozonation treatment time is 5-20 minutes.

[0052] In the above preparation steps, the stretchable substrate, the stretchable insulating layer, the stretchable polymer semiconductor layer and the photosensitive layer are all prepared by any one of the following methods: drop coating, spin coating, blade coating, roller coating, brush coating and stretch coating.

[0053] When preparing the stretchable substrate, the concentration of the elastomer polymer in the dispersion is 100-300 mg / mL; the dispersion medium in the dispersion is any one of toluene, xylene, chlorobenzene, cyclohexane, and n-hexane.

[0054] When preparing the stretchable insulating layer, the concentration of the elastomer polymer in the dispersion is 50-100 mg / mL; the dispersion medium in the dispersion is any one of toluene, xylene, chlorobenzene, cyclohexane, and n-hexane.

[0055] In preparing the stretchable polymer semiconductor layer, the concentration of the stretchable organic semiconductor blend system in the dispersion is 5–20 mg / mL; the dispersion medium in the dispersion is any one of chlorobenzene, o-dichlorobenzene, toluene, and xylene.

[0056] When preparing the photosensitive layer, the concentration of the perovskite quantum dots in the dispersion is 5–15 mg / mL.

[0057] In the above preparation steps, the stretchable gate electrode is prepared by spraying.

[0058] When preparing the stretchable gate electrode, the dispersion concentration of the carbon nanotubes is 0.05–0.3 mg / mL. The dispersion medium in the dispersion is any one of water, ethanol, isopropanol, or a mixture thereof.

[0059] The spraying conditions are as follows: the temperature of the substrate is 40-200℃, the distance between the spray gun nozzle and the substrate is 5-20mm, the spraying rate is 0.5-5mL / min, and the spraying amount is 0.5-5mL.

[0060] The stretchable van der Waals heterojunction source and drain electrodes are prepared by the following method: carbon nanotube source and drain electrodes are prepared by spraying on a substrate with a self-assembled molecular layer, and then an organic small molecule layer is coated on the surface of the carbon nanotube source and drain electrodes by vacuum evaporation, thereby realizing the stretchable van der Waals heterojunction source and drain electrodes.

[0061] The dispersion concentration of the carbon nanotubes is 0.05–0.3 mg / mL.

[0062] The spraying conditions are as follows: the temperature of the substrate is 40-200℃, the distance between the spray gun nozzle and the substrate is 5-20mm, the spraying rate is 0.5-5mL / min, and the spraying amount is 0.5-5mL.

[0063] In the above preparation steps, the heat bonding process is carried out in a vacuum drying oven;

[0064] The conditions for heat bonding are: vacuum degree of 0.1 to 10 Pascals, heat treatment temperature of 40 to 90°C, and heat treatment time of 0.1 to 1 hour.

[0065] Beneficial Effects: This invention provides a method for surface energy-induced self-assembly of perovskite quantum dots, preparing a uniform, compactly arranged, easily transferable, and flexible worm-like perovskite quantum dot film, enabling the application of highly crystalline granular perovskite quantum dot films in stretchable photodetectors. This invention also provides a high-performance stretchable high-energy photodetector and its fabrication method, which features a simple and low-cost fabrication process. The stretchable high-energy photodetector prepared by this invention exhibits ideal transfer characteristic curves, excellent photoelectric conversion performance, high tensile deformation resistance, good light transmittance and skin adhesion, and sensitive detection capability for high-energy photons (such as ultraviolet light, X-rays, and gamma rays), broadening the application prospects of perovskite quantum dots in the field of wearable photodetectors. Attached Figure Description

[0066] Figure 1 This is a schematic diagram of the structure of the stretchable high-energy photodetector based on perovskite quantum dot thin film provided by the present invention.

[0067] Figure 2 (a) is a scanning electron microscope (SEM) image of a conventional particulate CsPbBr3 quantum dot film prepared in Comparative Example 1; (b) is a scanning electron microscope (SEM) image of a worm-like CsPbBr3 quantum dot film prepared in Example 1 of this invention.

[0068] Figure 3 (a) is an atomic force diagram of a conventional particulate CsPbBr3 quantum dot film prepared in Comparative Example 1; (b) is an atomic force diagram of a worm-like CsPbBr3 quantum dot film prepared in Example 1 of this invention.

[0069] Figure 4 The transfer characteristic curves of the stretchable high-energy photodetector based on worm-like CsPbBr3 quantum dot thin film prepared in Example 1 of the present invention under different ultraviolet light intensities (ultraviolet light wavelength is 365nm).

[0070] Figure 5 The photocurrent-to-dark current ratio (a), photosensitivity (b), and photoresponsivity (c) of the stretchable high-energy photodetector based on worm-like CsPbBr3 quantum dot thin film prepared in Example 1 of this invention under different ultraviolet light intensities (ultraviolet light wavelength is 365nm).

[0071] Figure 6 The transfer characteristic curves of the stretchable high-energy photodetector based on a worm-like CsPbBr3 quantum dot thin film prepared in Example 1 of this invention are shown under no light and ultraviolet light illumination (ultraviolet light wavelength is 365 nm, ultraviolet light intensity is 0.037 mW / cm²). Figure 6 (a) Under unstretched conditions; Figure 6 (b) Under the condition of 50% elongation; Figure 6 (c) Under the condition of 100% elongation.

[0072] Figure 7 The photocurrent and photo-dark current ratio of the stretchable high-energy photodetector based on worm-like CsPbBr3 quantum dot thin film prepared in Example 1 of the present invention are shown. Detailed Implementation

[0073] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0074] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0075] This invention provides a stretchable high-energy photodetector based on perovskite quantum dot thin films and its fabrication method. The stretchable high-energy photodetector has a bottom-gate top-contact structure and, from bottom to top, includes a stretchable substrate, a stretchable gate electrode, a stretchable insulating layer, a stretchable polymer semiconductor layer, a stretchable van der Waals heterojunction source electrode and a drain electrode located on the same plane, and a photosensitive layer located in the channel, as shown in the figure. Figure 1As shown; the photosensitive layer is a worm-like perovskite quantum dot film, made of perovskite quantum dots with high absorption efficiency, high photoluminescence quantum efficiency and long exciton diffusion length characteristics, such as CsPbBr3 and CsPbI3 quantum dots.

[0076] This invention modifies the surface of a polydimethylsiloxane plate by hydroxylation through ultraviolet ozonolysis, thereby controlling the surface energy of the polydimethylsiloxane film and realizing a novel, uniform, compact, and easily transferable flexible worm-like perovskite quantum dot film. This breaks through the barrier that traditional highly crystalline granular perovskite quantum dot films are difficult to use in stretchable photodetectors, and opens up the application of perovskite quantum dot films in wearable electronic devices.

[0077] In this invention, the thickness of the photosensitive layer is 50-200 nm, preferably 80-120 nm;

[0078] In this invention, the thickness of the stretchable polymer semiconductor layer is 50-150 nm, preferably 60-90 nm;

[0079] In this invention, the thickness of the stretchable insulating layer is 1-3 μm, preferably 1-1.5 μm;

[0080] In this invention, the thickness of the organic small molecule layer is 10-60 nm, preferably 20-40 nm;

[0081] In this invention, the thickness of the stretchable substrate is 200μm-3mm, preferably 500μm-1.5mm.

[0082] The method for preparing the stretchable high-energy photodetector based on perovskite quantum dot thin film includes the following steps:

[0083] The first step is the fabrication of the stretchable substrate.

[0084] Stretchable substrates are prepared on substrates with self-assembled molecular layers by drop coating, spin coating, blade coating or roll coating.

[0085] The second step is the fabrication of the stretchable gate electrode.

[0086] A stretchable gate electrode is fabricated on a substrate with a self-assembled molecular layer by spraying.

[0087] The third step is the preparation of the stretchable insulating layer.

[0088] Stretchable insulating layers are prepared on substrates with self-assembled molecular layers by spin coating, blade coating, roller coating, brush coating, or stretch coating.

[0089] Step 4: Fabrication of the stretchable polymer semiconductor layer

[0090] Stretchable polymer semiconductor layers are prepared on substrates with self-assembled molecular layers by spin coating, blade coating, roller coating, brush coating, and stretch coating.

[0091] Step 5: Fabrication of the stretchable van der Waals heterojunction source and drain electrodes.

[0092] Carbon nanotube source and drain electrodes were prepared by spraying on a substrate with a self-assembled molecular layer. Then, an organic small molecule layer was coated on the surface of the carbon nanotube source and drain electrodes by vacuum evaporation, thereby realizing stretchable van der Waals heterojunction source and drain electrodes.

[0093] Step 6: Preparation of the photosensitive layer

[0094] Worm-like perovskite quantum dot films, i.e. photosensitive layers, are prepared on surface-hydroxylated polydimethylsiloxane plates by spin coating, blade coating, roller coating, brush coating, and stretch coating.

[0095] Step 7: Fabrication of a stretchable high-energy photodetector based on perovskite quantum dot thin film

[0096] Using pointed tweezers, the stretchable substrate is transferred from the substrate with the self-assembled molecular layer, and then gently placed over the stretchable gate electrode from one side. The stretchable gate electrode is then transferred onto the stretchable substrate using a thermal bonding method. Then, using the same method and steps, the stretchable insulating layer, the stretchable polymer semiconductor layer, and the stretchable van der Waals heterojunction source and drain electrodes are sequentially transferred onto the stretchable gate electrode. Finally, the photosensitive layer is transferred from the surface-hydroxylated polydimethylsiloxane plate into the channel between the stretchable van der Waals heterojunction source and drain electrodes, thus obtaining a stretchable high-energy photodetector based on a perovskite quantum dot thin film.

[0097] This invention provides a stretchable high-energy photodetector based on perovskite quantum dot thin films. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the technical solutions in the embodiments of this invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0098] The transfer characteristic curves of a stretchable high-energy photodetector based on perovskite quantum dot films were tested under both dark and high-energy ultraviolet light conditions, and the differences in its electrical performance under these conditions were compared. The calculations were performed using the following formula:

[0099] Photocurrent = Transistor current under illumination - Transistor current under no-light conditions

[0100] Photocurrent / Dark current = Transistor current under illumination / Transistor current under darkness

[0101] Light sensitivity = (Current of transistor under illumination - Current of transistor under no-light conditions) / Current of transistor under no-light conditions

[0102] Photoresponsivity = (Current under illumination - Current under no-light conditions) / Incident light power sensed in the transistor channel

[0103] Example 1:

[0104] The steps for fabricating a stretchable high-energy photodetector based on perovskite quantum dot thin films in this embodiment are as follows:

[0105] 1) Using a silicon wafer as a substrate, ultrasonically clean the wafer for 5 minutes at 30 watts and 40 kHz using detergent, deionized water, acetone and ethanol in sequence. After drying with a nitrogen gun, treat the cleaned silicon wafer with ultraviolet ozone for 20 minutes. Then, place the silicon wafer and octadecyltrimethoxysilane in the same petri dish and place the petri dish in a vacuum drying oven at 0.1 Pascal vacuum and 120°C for 3 hours. After the vacuum drying oven cools to room temperature, remove the petri dish to obtain a silicon wafer with a self-assembled molecular layer.

[0106] 2) Place the silicon wafer with the self-assembled molecular layer on a hot plate. Slowly draw 0.8 ml of SEBS-H1221 (purchased from Asahi Kasei Corporation, Japan) toluene solution (concentration 180 mg / mL) using a 1 mL syringe and uniformly drop it onto the silicon wafer with the self-assembled molecular layer. Then, maintain the temperature at 50°C for 3 hours, followed by 90°C for 1 hour to obtain a stretchable substrate with a thickness of 1.2 mm. (Note: To ensure that no air bubbles appear in the prepared stretchable substrate, the drop-coating rate should be as slow as possible. The last two drops of SEBS-H1221 toluene solution should not be dropped onto the silicon wafer with the self-assembled molecular layer.)

[0107] 3) Place the silicon wafer with the self-assembled molecular layer on a hot stage at 80°C for 5 minutes. Use a 5mL pipette to transfer 2mL of carbon nanotube P3-SWNT isopropanol solution (0.2mg / mL) into the volume chamber of the spray gun. Then, spray it uniformly onto the silicon wafer with the self-assembled molecular layer at a rate of 0.15mL / min (wherein, the distance between the spray gun nozzle and the silicon wafer is 6mm) to obtain the stretchable gate electrode.

[0108] 4) Place the silicon wafer with the self-assembled molecular layer at the center of the spin coater rotor. Use a 1 mL pipette to draw 400 μL of SEBS-H1052 cyclohexane solution (concentration 80 mg / mL). Then, uniformly drop 350 μL of the SEBS-H1052 cyclohexane solution onto the silicon wafer with the self-assembled molecular layer. Start the spin coater and maintain a speed of 1000 rpm for 1 minute. Finally, remove the silicon wafer and anneal it on a hot plate at 80°C for 1 hour to obtain a stretchable insulating layer with a thickness of 1.2 μm.

[0109] 5) Place the silicon wafer with the self-assembled molecular layer in the center of a spin coater, and use a 50 μL pipette to drop 30 μL of a chlorobenzene solution of poly(2,5-bis(2-octyldodecyl)-3,6-di(thiophene-2-yl)dionepyrrolo[3,4-c]pyrrolo-1,4-dione-3-thiophenolo[3,2-b]thiophene) / hydrogenated styrene-butadiene block copolymer (wherein the mass ratio of the two polymers is 5:5 and the concentration is 10 mg / ml) onto the silicon wafer. Then spin coat at 2000 rpm for 1 minute. Finally, place the silicon wafer on a hot plate and anneal at 150°C for 20 minutes to obtain a stretchable polymer semiconductor layer with a thickness of 80 nm.

[0110] 6) Place the silicon wafer with the self-assembled molecular layer on a magnet, and then place the mask on the silicon wafer, thus firmly attaching the mask to the silicon wafer with the self-assembled molecular layer. Gently place the magnet and silicon wafer on a hot stage at 110°C for 15 minutes. Then, use a 5mL pipette to draw 2mL of an isopropanol solution of carbon nanotubes P3-SWNT (concentration 0.15mg / mL) and place it in the volume chamber of an airbrush. Spray the solution evenly onto the silicon wafer with the self-assembled molecular layer at a rate of 0.03mL / min (wherein, the distance between the airbrush nozzle and the silicon wafer is 9mm). Then, gently place the silicon wafer with the patterned carbon nanotube source and drain electrodes into a vacuum coating machine (Note: When transferring the silicon wafer to the vacuum coating machine, handle it gently to avoid movement of the mask and the silicon wafer). Elevate the vacuum to 5×10⁻⁶. -4 Below Pascal, a patterned stretchable van der Waals heterojunction source and drain electrode can be obtained by using vacuum thermal evaporation to deposit a pentabenzene layer at a rate of 0.8 angstroms per second to a thickness of 20 nm.

[0111] 7) Place the polydimethylsiloxane plate in a UV ozone cleaner for 7 minutes. Then, place the surface-hydroxylated polydimethylsiloxane in the center of a homogenizer and add 20 μL of a hexane solution (10 mg / mL) of CsPbBr3 onto the surface-hydroxylated polydimethylsiloxane plate using a 50 μL pipette. Spin coat at 1500 rpm for 1 minute. Finally, place the polydimethylsiloxane plate on a hot plate and anneal at 60°C for 5 minutes to obtain a worm-like CsPbBr3 quantum dot film with a thickness of 100 nm.

[0112] 8) Gently transfer the stretchable substrate from the substrate with the self-assembled molecular layer using pointed tweezers. Then, gently cover the stretchable substrate onto the stretchable gate electrode from one side and place it in a vacuum drying oven with a vacuum degree of 0.1 Pascals at 60°C for 20 minutes. After the temperature drops to room temperature, gently transfer the stretchable substrate off using pointed tweezers. Through this process, the stretchable gate electrode can be transferred onto the stretchable substrate. Then, using the same method and steps, sequentially transfer the stretchable insulating layer, the stretchable polymer semiconductor layer, and the stretchable van der Waals heterojunction source and drain electrodes located on the same plane onto the stretchable gate electrode. Finally, transfer the photosensitive layer from the surface-hydroxylated polydimethylsiloxane plate into the channel between the stretchable van der Waals heterojunction source and drain electrodes to obtain a stretchable high-energy photodetector based on perovskite quantum dot thin film.

[0113] Comparative Example 1: Following the exact same preparation method as Example 1, except that the hydroxylated polydimethylsiloxane plate in step 7) was replaced with a silicon wafer, a 120 nm thick granular CsPbBr3 quantum dot film was obtained.

[0114] Figure 2 (a) and (b) are scanning electron microscope images of the conventional granular CsPbBr3 quantum dot film prepared in Comparative Example 1 and the worm-like CsPbBr3 quantum dot film prepared in Example 1, respectively. Figure 3 (a) and (b) are atomic force maps of the conventional granular CsPbBr3 quantum dot film prepared in Comparative Example 1 and the worm-like CsPbBr3 quantum dot film prepared in Example 1, respectively. Figure 2 and Figure 3 Analysis shows that the perovskite quantum dot film prepared in Example 1 has a uniform, compactly arranged, worm-like morphology, completely different from the traditional granular perovskite quantum dot film prepared in Comparative Example 1. Traditional granular CsPbBr3 quantum dot films are difficult to transfer, and therefore cannot be used for the fabrication of stretchable photodetectors. However, the worm-like CsPbBr3 quantum dot film prepared in Example 1 of this invention can be completely transferred. Figure 4Analysis shows that the stretchable high-energy photodetector based on worm-like CsPbBr3 quantum dot thin films prepared in Example 1 exhibits ideal transfer characteristic curves under no-light conditions, and the source-drain current of the photodetector gradually increases with the increase of 365nm ultraviolet light intensity. This is mainly because the number of photogenerated carriers in the perovskite quantum dot thin film increases with the increase of light intensity, resulting in an increase in the number of electrons trapped at the interface between the perovskite quantum dot thin film and the polymer semiconductor layer, and the number of holes transferred to the polymer semiconductor layer, ultimately leading to an improvement in hole transport efficiency between the source and drain electrodes. Figure 5 The results show that the light conversion characteristics (photocurrent-to-dark-current ratio, photosensitivity, and photoresponsivity) of the stretchable high-energy photodetector prepared in Example 1 exhibit significant gate voltage and ultraviolet light dependence, with the photocurrent-to-dark-current ratio reaching 3 × 10⁻⁶. 6 This is one of the highest values ​​reported for photodetectors to date. More importantly, the stretchable high-energy photodetector based on worm-like CsPbBr3 quantum dot films prepared in Example 1 exhibits high strain tolerance, displaying ideal transfer characteristic curves and relatively stable light conversion performance even under tensile strains up to 100%. Figure 6 For example, the photodetector's dark current ratio at 0% and 100% tensile strain is 3 × 10⁻⁶. 6 and 8×10 5 ( Figure 7 The slight decrease in efficiency is mainly due to the increased channel area and reduced effective coverage area of ​​the perovskite quantum dots under tensile strain, thus reducing carrier transport efficiency. Generally, tensile strain of 0% to 25% is suitable for most wearable electronic products. Therefore, the stretchable high-energy photodetector based on worm-like CsPbBr3 quantum dot thin films provided by this invention can meet practical application requirements.

Claims

1. A method for surface energy-induced self-assembly of perovskite quantum dots, comprising the following steps: using a perovskite quantum dot dispersion as raw material, a solution deposition method is used to prepare a worm-like perovskite quantum dot film on a surface-hydroxylated polydimethylsiloxane plate; The surface-hydroxylated polydimethylsiloxane plate is obtained by subjecting the polydimethylsiloxane plate to ultraviolet ozonolysis treatment; The perovskite quantum dots are selected from perovskite quantum dots with high absorption efficiency, high photoluminescence quantum efficiency, and long exciton diffusion length, specifically selected from CsPbBr3 and / or CsPbI3 quantum dots; The concentration of perovskite quantum dots in the perovskite quantum dot dispersion is 5~15 mg / mL, and the dispersion medium is selected from any one of toluene, cyclohexane, cyclopentane and n-hexane; The method further includes: After preparation, the substrate with the thin film on its surface is annealed. The annealing conditions are: annealing at 40-80 °C for 1-10 minutes on a hot table.

2. The method according to claim 1, characterized in that: The solution deposition method includes any one of the following: drop coating, spin coating, blade coating, roller coating, brush coating, and stretch coating; Alternatively, the ultraviolet ozonation treatment time is 5-20 minutes.

3. The worm-like perovskite quantum dot film prepared by the method of claim 1 or 2.

4. A stretchable high-energy photodetector based on perovskite quantum dot thin film, the structure of which, from bottom to top, includes a stretchable substrate, a stretchable gate electrode, a stretchable insulating layer, a stretchable polymer semiconductor layer, a stretchable van der Waals heterojunction source and drain electrode located on the same plane, and a photosensitive layer located in the channel formed by the stretchable van der Waals heterojunction source and drain electrode. The photosensitive layer is the worm-like perovskite quantum dot film as described in claim 3; The stretchable high-energy photodetector has a bottom grid top contact structure.

5. The stretchable high-energy photodetector according to claim 4, characterized in that: The high-energy light in the stretchable high-energy photodetector is high-energy photon, including ultraviolet light, X-rays or gamma rays; The thickness of the photosensitive layer is 50-200 nm; The stretchable polymer semiconductor layer is made of a stretchable organic semiconductor blend system; The thickness of the stretchable polymer semiconductor layer is 50-150 nm; Both the stretchable substrate and the stretchable insulating layer are made of elastomeric polymers; The thickness of the stretchable substrate is 200 µm-3 mm; The thickness of the stretchable insulating layer is 1-3 µm; The stretchable van der Waals heterojunction source and drain electrodes are parallel heterojunction structures composed of single-walled carbon nanotubes and small organic molecules. The single-walled carbon nanotubes include any one of P2-SWNT, P3-SWNT, P5-SWNT, P7-SWNT, P8-SWNT, and P9-SWNT; The organic small molecules include any one of tetraphenyl, pentaphenyl, copper phthalocyanine, vanadium titanyl cyanocyanate, rubrene, pentathiazole and PCBM; The organic small molecules are deposited on the surface of the single-walled carbon nanotubes by vacuum evaporation. The thickness of the layer formed by the organic small molecules is 10-60 nm; The stretchable gate electrode is made of carbon nanotubes; The carbon nanotubes used to prepare the stretchable gate electrode are single-walled carbon nanotubes, including any one of P2-SWNT, P3-SWNT, P5-SWNT, P8-SWNT, and P9-SWNT.

6. The stretchable high-energy photodetector according to claim 5, characterized in that: The stretchable organic semiconductor blend system is prepared by solution blending of a conjugated polymer and an elastomer polymer. The conjugated polymer is selected from any one of poly(2,5-bis(2-octyldodecyl)-3,6-bis(thiophen-2-yl)dionepyrrole[3,4-c]pyrrole-1,4-dione-alt-thiophene[3,2-b]thiophene), poly[(2,5-bis(5-decyl-1-pentyl)–3,6-bis(thiophen-2-yl)pyrrole[3,4-c]pyrrole-1,4(2H,5H)-dione)-alt-((E)–1,2-bis(thiophen-2-yl)ethane], poly(2,5-bis(3-alkylthiophen-2-yl)thiophene[3,2-b]thiophene, poly(tetrathiophene acetate dionepyrrole), polyisoindigo dithiophene (PII2T) and poly(3-hexylthiophene); The elastomer polymer is any one of hydrogenated styrene-butadiene block copolymer, polydimethylsiloxane, natural rubber, styrene-butadiene rubber, ethylene propylene rubber, butyl rubber, and polyurethane elastomer; The blending mass ratio of the conjugated polymer to the elastomer polymer is 1~9:1~9; The solvent used in the solution blending method is any one of chlorobenzene, o-dichlorobenzene, toluene, and xylene; The solution blending conditions are as follows: stirring temperature 50-100 °C, stirring speed 100-1000 rpm; stirring time 0.5-5 hours. Alternatively, the elastomer polymer is selected from any one of polydimethylsiloxane, hydrogenated styrene-butadiene block copolymer, styrene-butadiene rubber, natural rubber, ethylene propylene rubber, butyl rubber, and thermoplastic polyurethane elastomer; The solvent used to prepare the stretchable substrate and the stretchable insulating layer is any one of toluene, xylene, chlorobenzene, cyclohexane and n-hexane; Alternatively, the vacuum evaporation conditions are: a vacuum degree of 10. -4 -10 -6 Pascal, evaporation rate is 1-5 angstroms / second.

7. A method for fabricating the stretchable high-energy photodetector according to any one of claims 4-6, comprising the following steps: 1) The stretchable substrate, the stretchable gate electrode, the stretchable insulating layer, the stretchable polymer semiconductor layer, the stretchable van der Waals heterojunction source, and the drain electrode are respectively fabricated on a substrate with a self-assembled molecular layer; 2) The photosensitive layer is prepared on a surface-hydroxylated polydimethylsiloxane plate; 3) Using pointed tweezers, transfer the stretchable substrate from the substrate with the self-assembled molecular layer, and then gently cover the stretchable gate electrode from one side; transfer the stretchable gate electrode to the stretchable substrate using a thermal bonding method; then, using the same method and steps, sequentially transfer the stretchable insulating layer, the stretchable polymer semiconductor layer, and the stretchable van der Waals heterojunction source and drain electrodes located on the same plane to the stretchable gate electrode; finally, transfer the photosensitive layer from the surface-hydroxylated polydimethylsiloxane plate to the channel of the stretchable van der Waals heterojunction source and drain electrodes to obtain the final product.

8. The preparation method according to claim 7, characterized in that: In step 1), the substrate is made of any one of silicon wafer, glass, ceramic, metal, quartz and hard alloy. The substrate is ultrasonically cleaned sequentially with detergent, deionized water, acetone and ethanol, dried with a nitrogen gun, and then subjected to ultraviolet ozonolysis to obtain a clean substrate. The substrate with the self-assembled molecular layer is prepared by heating or immersing the clean substrate in a solution under vacuum conditions with any one of octadecyltrimethoxysilane, octadecyltrichlorosilane, octadecyltrichlorosilane and phenyltrichlorosilane. The stretchable substrate, the stretchable insulating layer, the stretchable polymer semiconductor layer, and the photosensitive layer are all prepared by any one of the following methods: drop coating, spin coating, blade coating, roller coating, brush coating, and stretch coating; the solution used is toluene, xylene, methane, chloroform, dichloromethane, n-hexane, or cyclohexane. The stretchable gate electrode is prepared by spraying. The solvent used to prepare the stretchable gate electrode is water, ethanol, isopropanol, or a mixture thereof; The stretchable van der Waals heterojunction source and drain electrode are prepared by the following method: carbon nanotube source and drain electrode are prepared by spraying on a substrate with a self-assembled molecular layer, and then an organic small molecule layer is coated on the surface of the carbon nanotube source and drain electrode by vacuum evaporation. The spraying conditions for preparing the stretchable gate electrode and the stretchable van der Waals heterojunction source and drain electrodes are as follows: substrate temperature is 40-200 °C, distance between spray gun nozzle and substrate is 3-20 mm, spraying rate is 0.5-5 mL / min, and spraying amount is 0.5-5 mL.

9. The preparation method according to claim 7 or 8, characterized in that: In step 2), the surface-hydroxylated polydimethylsiloxane plate is achieved by subjecting the surface of the polydimethylsiloxane plate to ultraviolet ozonolysis treatment. In step 3), the heat bonding process is carried out in a vacuum drying oven; The conditions for heat bonding are: vacuum degree of 0.1~10 Pascal, heating temperature of 50~150 °C, and heating time of 0.5~5 hours.

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